The most important thing to remember when using this (or any other) glossary is that just because some aspect of an organism is dignified by a sesquipedalian term, this by no means signifies that the term refers to an interesting part of "reality". As Hesse et al. (2009b: p. 27) noted "Nature itself neither needs categories nor has any knowledge of them" and "categories are artifical and always delimited by an individual or collective convention". Humans make and define botanical terms, and we use them to facilitate communication, although all too often they seem to be as much an impediment to our understanding as anything else. This raises a second important point. As mentioned in the Introduction, definitions should as far as possible follow current usage, rather than etymology or original definitions (see, e.g. Rickett 1954-56). However, current usage is all too often not consistent, and this is one of the major failings of botanical terminology. As Rickett (1954 p. 2; emphasis in original) noted, "To be uncertain whether "glabrous" means "free from hairs and roughness" or only "free from hairs" is as bad as if π [pi] should stand sometimes for the ratio of a circle to its diameter and sometimes for something else; or as if Cu meant sometimes "copper" and sometimes "brass". Yet this is the state of affairs in botany today". Over forty years later, this is still true (see e.g. Castel et al. 2010 for inflorescences), but we need to attempt to reach consensus, otherwise communication with ecologists and others using botanical information will be seriously hindered.

With any glossary, there is always the question of what to include and what to exclude. We list those terms used in these pages, some of their common synonyms, and also some other terms commonly used in the literature that has been consulted. When there are alternative terms for the one structure, we have chosen the term that seems easiest to use or makes most obvious sense, thus we have prefered "straight" over "orthotropous", since the latter seems almost an oxymoron (even "atropous" would be better...), and "odd-pinnate" for "imparipinnate" since the former is closer to plain language (in english, at least) yet is no less precise. There will always be tensions when it comes to terms used to describe specific features of the sporophytic and gametophytic generations. Thus "nucellus" is prefered over "megasporangium wall", although the latter is technically what a nucellus is, and "embryo sac" over "female gametophyte" since the former term is almost always used in the literature dealing with flowering plants. The definitions agree as far as possible with those in the Plant Ontology Consortium (2004 onwards).

Settling on definitions is often not easy. Thus there is some dispute among wood anatomists over exactly what terms to use and how to define them (c.f. Wheeler et al. 1989; Metcalfe & Chalk 1989; Carlquist 2001, 2010). Other terms have definitions that can be distinguished only with difficulty, or there are alternative sets of terms that can be used when looking at the same structures, but from different points of view (e.g. c.f. a superior ovary and a hypogynous flower), or simply just alternative sets of terms that can be used... Finally, it must be repeated that it should not be assumed that the terms below refer to anything "real" or interesting in the world, even when assembled into clean-looking contrast sets (see the Introduction for more discussion).

Since the focus is on terms used when discussing the characters of and relationships between major clades, many of the terms used when describing species are omitted. However, Stearn (1992) remains a particularly useful source for definitions here. Along the same lines, the focus here is not on ecology, but functional aspects of ecology in particular may be mentioed. A number of the terms used by functional ecologists are mentioned by Pérez-Harguindeguy et al. (2013), although the focus there is on the important issue of the measurement of the variables mentioned.

The basic arrangement is alphabetical, however, terms that start with contractions like P-protein, CAM, etc., are to be found at the beginning of the entries for the relevant letter - exceptions are contractions that refer to chemical elements like N[itrogen] and C[arbon]. Prefixes and suffixes are to be found at the appropriate places within the entries for their first letters

The glossary functions hierarchically, and to a certain extent it is like an ontology. If in an entry, one finds "see", this is followed by an enumeration of the terms used in to describe the variants of the structure just described. Thus under accessory buds, one finds "see collateral, superposed", and there are links to these two terms that describe common variants in the arrangement of such buds. c.f., on the other hand, is followed by a listing of contrasting terms used to describe the variants of the structure just described. Thus after the definition of abaxial, we find "c.f. adaxial, lateral, median", so linking to the other terms used to describe the positions of parts of, for example, position in a flower with repect to the axis. However, a few terms are included in contrast sets simply because that is common practice, even if logically they should be excluded.

Thus an entry like "amphiparacytic: of paracytic stomata where the subsidiary cells are parallel to the long axis of the stoma and completely surround the latter, c.f. brachyparacytic" first defines the term, making it clear that it is a subtype of paracytic stomata, to which the reader can go for a definition (and also to stomata, as well as subsidiary cells), while being contrasted with brachyparacytic stomata, the other member of the immmediate contrast set, to which the reader can also go for a definition.

Some synonymy is indicated, e.g. "calcar, calcarate = spur, spurred."

Information for this glossary has been taken from many places. Informative general morphological glossaries or other sources are Lawrence (1951), Esau (1965, 1977, glossary here particularly useful), Radford et al. (1974), Endress (1994b), Harris and Harris (1994), Hickey and King (2000), Judd et al. (2016), Bell and Bryan (1991, 2008: beautiful illustrations), Beentje (2012) and of course Stearn (1992). Metcalfe and Chalk (1979, 1983) also provide much useful information. Chemical formulae and definitions have been taken from American Chemical Society (2004), Harborne and Turner (1984), Harborne and Baxter (1992), Harborne et al. (1999), Robinson (1991), Siegler (1998, 2004), Smith (1976) and Walton and Brown (1999), see also Berenbaum (1999: furanocoumarins), Connolly and Hill (terpenoids), Glasby (1975-1983: alkaloids), Langenheim (2003: resins), and Schleimann (2004: mycorrhizal biochemistry). For wood anatomy, see Wheeler et al. (1989: hardwoods, see also Miller & Baas 1981 and Miller 1981 for characters, coding and computerization), Richter et al. (2004: softwoods) and Crivellaro and Schweingruber (2015: flowering plants in general), and also InsideWood: An Internet Accessible Wood Anatomy Database http://www.lib.ncsu.edu/insidewoood/. For anatomy and morphology, see Dickison (2000), for hairs and indumentum, see Payne (1978), Hewson (1988), Stearn (1992), etc., for stomata, etc., see the Leaf Architecture Working Group (1999), for phyllotaxis, see Jean (1994: Appendix 1), for leaf architecture in general, see Ellis et al. (2009), for leaf teeth, see Hickey and Wolfe (1975), for venation, see Hickey (1979), for life forms, see Raunkiaer (1934), for terms used in canopy biology, see Moffett (2000), for inflorescences in particular, but also much else, see Weberling (1989), for pollen terminology, which is particularly difficult, see Reitsma (1970), Walker and Doyle (1975), Hesse et al. (2009b, especially useful) and Halbritter et al. (2017), for fruit, see Spjut (1994: all his terms are not included below, but his work helped catalyze my thoughts, 2003 onwards) and for monocot seedlings, see Tillich (2007). And last, but by no means least, the OED (Simpson & Weiner 1989) and Wikipedia have been very helpful!

For variation in seed plants of the characters defined in the glossary - and more about many of the characters - see the "Characters" page.

We built this glossary using the excellent Flora of Australia Online Glossary as our inspiration. We are very grateful to to the Australian Biological Resources Study and also to the artists who drew the illustrations for some of the terms in that glossary for permission to use the Glossary. Selected links to illustrations in the Flora of Australia Online Glossary are included here (indicated by  ); the illustrators of these images are indicated on the images themselves. Gregor Hagedorn and Volker Bittrich in particular have provided useful comments.

A

a- (prefix): without.

ab- (prefix): away from.

abaxial: of the side or surface of an organ like a petal or organ system such as a branch, facing away from the axis that bears the organ or organ system, c.f. adaxial, lateral, median, a useful set of positional descriptors.

abscission: the normal shedding from a plant of an organ that is mature or aged, e.g. a ripe fruit, an old leaf, see also cladoptosis.

acalymmate: of a pollen tetrad or polyad, when the ectexine is separately differentiated on each grain, there being no common covering of the pollen mass, c.f. calymmate.

acaulescent: of habit, without any above-ground stem execept for an inflorescence axis, where present, leaves and inflorescence arising together at ground level, c.f. arborescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, suffrutescent, schopfbaum, shrub, subshrub, tree, vine, see also life forms.

accessory bud(s): one or more buds other than the normal single bud occuring in the leaf axil, c.f. adventitious, supernumerary, see collateral, superposed (arrangement of the buds).

accessory cell = subsidiary cell.

accessory fruits: fruits, whether derived from a single flower or several, with tissue that is other than carpellary in origin, e.g. the hypocarp, see also anthocarp, c.f. aggregate fruits, multiple fruits, simple fruits.

accrescent: continuing to increase in size after maturity, as the calyx of some plants after flowering, c.f. caducous, deciduous, deliquescent, fugacious, marcescent, persistent.

accumbent: of an embryo that is folded so that the radicle lies against the edges of the two cotyledons, c.f. conduplicate, diplecolobous, incumbent.

acervulus: a variant of a scorpioid cyme, a monochasial cymose inflorescence with 2-10 or more sessile flowers borne close together in two vertical rows (Uhl & Moore 1978).

acetate: a salt, ester or the conjugate base of acetic acid.

Acetate, C2 H3 O2.

acetogenins: polyketides derived from acetate with 35-37 carbon atoms in a single almost unbranched chain, substituted by 6-8 oxygen atoms.

Acetogenin-G, C19 H22 O3.

Mucoxin, C37 H66 O7.

acetylenes: the simplest of a class of straight-chain triple-bonded hydrocarbons, see also cyclopropanes.

Acetylene, C2 H2.

achene: specifically, a dry, indehiscent fruit formed from a superior ovary of one carpel and containing one seed which is free from the pericarp except at the funicular end, more broadly, dry one-seeded fruits in general, whether formed from one or more carpels and superior or inferior ovaries, see caryopsis, cypsela, nut, utricle for variants which are also often called simply "achenes".

achlamydeous: of a flower, lacking a perianth parts, usually best to describe as such, c.f. dichlamydeous, heterochlamydeous, monochlamydeous.

acicular = needle-like.

acorn: a nut or achene sitting in or more or less surrounded by a cup formed by fused bracts, etc. (see Fagaceae).

acro- (prefix): extreme, extremities (e.g. apex).

acrocentric: a chromosome in which the centromere is near one end, the spindle fibers attaching there during nuclear division, c.f. holocentric, metacentric, and telocentric.

acrodromous: of palmate leaf venation, with two or more primary or strongly developed secondary veins running in convergent arches towards the apex, c.f. actinodromous.

acrogyny: in monoecious plants with mixed inflorescemces, the female flowers being borne in the apical part of the inflorescence - the unusual condition; rarely used, while basigyny seems never to be used...

acropetal: produced or differentiated in succession towards the apex of an organ, e.g. of an inflorescence, with flowers arising or developing in a sequence beginning at the base and proceeding towards the apex, see also centripetal, c.f. basipetal.

acroscopic = antrorse.

acrotonic: a branching pattern in which the uppermost buds of a season's growth/innovation grow out most strongly, as in Sassafrass, c.f. basitonic, mesotonic.

acteoside = verbascoside.

actinocytic: of stomata, with five or more somewhat radially enlarged or elongated subsidiary cells surrounding the guard cells, c.f. allelocytic, anisocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, staurocytic, stephanocytic, tetracytic.

actinodromous: of palmate leaf venation, with three or more primary veins arising from at or near the base, ascending or diverging, whether or not reaching the margin, c.f. acrodromous.

actinomorphic = polysymmetrical.

actinostele: a variant of a protostele in which the xylem forms a more or less star-shaped central mass, with phloem between the arms, c.f. haplostele, plectostele.

aculeate = prickly, c.f. muricate.

acumen: of the apex of a structure, a long, narrowly tapering point with convex sides, hence acuminate, c.f. acute, attenuate, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

acute: of the apex or base of a structure, terminating in a distinct but not protracted point, the coverging sides concave and joining at an angle of less than 90^o, c.f. acumen, attenuate, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

acyclic = spiral.

acylation: stabilization by the introduction of an acid radical from acids such as coumaric, ferulic, or caffeic acids into e.g. acylated anthocyanins.

Cyanidin 3-dimalonylglucoside, C27 H25 O17.

ad- (prefix): towards.

adaxial: of the side or surface of an organ like a petal or organ system such as a branch, facing towards the axis that bears the organ or organ system, c.f. abaxial, lateral, median, a useful set of positional descriptors.

addorsed (prophyll) = adaxial (prophyll).

adherent: when tissues or organs of different kinds are stuck together, but without organic fusion, c.f. appressed, adnate, coherent, connate, connivent, fasciate, fasciculate, fastigiate, phalangiate.

admedial: towards the midline of the lamina, c.f. exmedial.

adnate: a type of concrescence when tissues of one organ are organically fused to those of another organ of a different kind, as a stamen adnate to a petal, c.f. connate, also adherent, appressed, coherent, connivent, fasciate, fasciculate, fastigiate, phalangiate.

Adoxa: an embryo sac type, the types based on variation in megasporogenesis and megagametogenesis, tetrasporic and 8-nucleate, all nuclei haploid, c.f. Allium, Drusa, Endymion, Fritillaria, Oenothera, Penaea, Peperomia, Plumbagella, Plumbago, Polygonum, Schisandra.

aduncate = hooked.

advanced (of characters, not recommended) = apomorphy or derived.

adventitious: arising in "abnormal" positions and in "exceptional" circumstances, e.g. roots arising from the shoot system, buds arising elsewhere than in axils of leaves, however, the roots that characteristically occur along the stems of a number of prostrate herbs (as in most monocots = secondary root system), often in fixed positions, are also often called adventitious, which is not at all helpful, see also accessory, supernumerary.

adventitious bud: a bud that develops endogeneously and in a non-axillary position from previously non-meristematic tissue, often in response to damage or changed environmental conditions, see epicormic budc.f. preventitious.

adventitious (poly)embryony: of agamospermous reproduction, the production of an embryo/seed directly from somatic tissue of the ovule without fertilisation, c.f. apogamy, apospory, diplospory, polyembryony.

adventive: introduced to an area recently, whether or not established c.f. endemic, native, introduced, naturalised.

aerenchyma: tissue incorporating large, gas-filled spaces interspersed between the cells, often forming characteristic arrangements, c.f. collenchyma, parenchyma, sclerenchyma.

aeschynomenoid: a type of nodule caused by nitrogen-fixing bacteria in Fabaceae, more or less ephemeral, with a subcortical growing zone, oblate, lacking lenticels, and with a narrow point of attachment, c.f. caesalpinioid, crotalarioid, desmodioid, and lupin type.

aestivation: the arrangement of parts in a bud, in particular, in a flower, how sepals and petals or their lobes overlap relative to one another in an unopened bud, c.f. vernation, see cochleate, contorted, contortiplicate, crumpled, decussate, imbricate, induplicate, open, quincuncial, reduplicate, valvate - some of these can also be used to described how leaves overlap in a bud; see also equitant, convolute, obvolute, see anaphoric and cataphoric (rotation of leaves in bud)..

after-ripening: of germination, when a period of dormancy of the seed and/or growth of the embryo is needed before germination will occur, c.f. recalcitrant.

agamospermy: a kind of apomictic (s.l.) reproduction, the development of seeds from ovules without fertilization, equals apomixis s. str, see adventitious embryony, apospory, diplospory, polyembryony.

aggregate fruit: a cluster of fruits formed from more than one flower, = multiple fruit, syncarp, so some redundancy here, c.f. accessory fruit, simple fruit.

aggregate ray: a group of rays in the wood that appear to be jusy a single ray at low magnification but actually consist of smaller rays closely aggregated.

aglycone: the non-carbohydrate group of a glycoside which appears on its hydrolysis (sometimes called aglucone).

agmatoploid: chromosome number increase by fragmentation, especially when the chromosomes are holocentric, c.f. allopolyploid, aneuploid, autopolyploid, diploid, demiduplication, dysploid, endopolyploidy, and haploid, polyploid, symploid, see also mesopolyploid and palaeopolyploid.

ala, alate = wing, winged.

alar, loosely = axillary (Hickey & King 2000), e.g. see axillary bud, but a confusing term.

albumen = endosperm.

albuminous cell = Strasburger cells.

alditol: a polyol or sugar alcohol with a linear chain of carbon atoms, an acyclic polyol, c.f. cyclitol, see arabitol, dulcitol, glycerol, mannitol, sorbitol and xylitol.

aldose: a monosaccharide or simple sugar with but a single aldehyde (C=O) group, inc. dioses, trioses, pentoses, and hexoses.

aleurone: aleurone layer, the outermost layer(s) of the endosperm (or, according to Werker [1997], the innermost layer of the nucellus), living cells containing proteins, the other cells being more or less dead and with much thickened walls, the lumen being more or less occluded e.g. by galactomannans (a hemicellulose), c.f. chalazal cyst, haustorium, see also aleurone grain, a garin-like structure conating proteins, etc.

aliform: of paratracheal axial parenchyma, the parenchyma cells associated with the vessels forming a wing-shaped mass in transverse section, c.f. banded.

alkanes: simple hydrocarbons, CH₃ (CH₂)_n CH₃, where n = 25-35.

alkaloids: organic, nitrogenous-containing bases, usually with a heterocyclic ring of some kind, but with little in common other than the posession of N, usually somewhat basic, and divided into three main categories: 1) true alkaloids - nitrogen-containing heterocyclic compounds derived from an amino acid whence the nitrogen comes, e.g. benzylisoquinoline alkaloids, tropane alkaloids, quinolizidine alkaloids, 2) protoalkaloids - derived from amino acids, again, the nitrogen donor, but lacking a heterocyclic ring, 3) pseudoalkaloids - derived from terpenes, sterols, aliphatic acids, nicotinic acid, or purines, and nitrogen not coming form amino acids. Note that similar alkaloids can have quite different biosynthetic pathways, indeed, alkaloids are rather like species - you know what they are, but cannot define them...

alkannin: a naphthoquinone derived from the p-hydroxybenzoic acid pathway (S = shikonin isomer), the coloring ingredient of alkanet; alkannin paper is an indicator of acidity, alkalis turning the paper blue, acids red (see the color changes as flowers of some Boraginaceae-Boraginoideae age).

Alkannin, C16 H16 O5.

allelocytic: of stomata, with an alternating complex of three or more C-shaped subsidiary cells of graded sizes surrounding the guard cells, see diallelocytic and parallelocytic, c.f. actinocytic, anisocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, staurocytic, stephanocytic, tetracytic.

allitol: a carbohydrate product resulting from the reduction of the aldehyde functional group in D-allose.

Allitol, C6 H14 O6.

Allium: an embryo sac type, the types based on variation in megasporogenesis and megagametogenesis, bisporic (the chalazal dyad) and 8-celled, all nuclei haploid, c.f. Adoxa, Drusa, Endymion, Fritillaria, Oenothera, Penaea, Peperomia, Plumbagella, Plumbago, Polygonum, Schisandra.

allogamy: fertilisation involving gametes from different flowers or plants, a rather vague term, c.f. cross pollination, geitonogamy, c.f. also autogamy, self pollination.

allopatric: of the distributions of two taxa or populations, when the areas inhabited are mutually exclusive, c.f. parapatric, sympatric.

allopolyploid: a plant with a chromosome number that is the product of the addition of the diploid numbers of the parent plants, hybridisation having been involved, c.f. aneuploid, agmatoploid, autopolyploid, diploid, demiduplication, dysploid, endopolyploidy, haploid, polyploid, symploid, see also mesopolyploid and palaeopolyploid.

allorhizic: or taproot system - where the main root is continuous with respect to the shoot/longitudinal axis of the embryo, the radicle keeping on growing, c.f. homorhizic.

alternate: of leaves or other lateral organs, borne singly at different heights on the axis, when used to describe leaf insertion, often vague (and so not recommended), including the more precise spiral and distichous, c.f. also bijugate, decussate, opposite, pseudoverticillate, spiromonistichous, tristichous, whorled.

alternate: of floral parts, with members of adjacent whorls borne on alternating radii, e.g. used when describing the position of stamens with respect to petals (alternipetalous), sepals (alternisepalous), etc., c.f. opposite.

alternate: of pits, when they are in diagonal rows and, when crowded, hexagonal in surface view, c.f. opposite.

alternation of generations: the characteristic life cycle of land plants or embryophytes: the haploid plant body produces gametes via mitotic divisions, the gametes fuse producing the multicellular diploid sporophyte, this produces haploid spores after meiotic events, and the spores germinate to produce the multicellular haploid gametophyte again; a haplodiplontic life cycle.

alveolate: pitted or honeycombed on the surface or throughout the structure, esp. for seeds, c.f. aulacospermous, bothrospermous, also ruminate, condyle.

alveolaee: of a pollen grain, with chambers in the infratectum of the ectexine that are surrounded by more or less complete partitions, hence alveolate pollen, c.f. columellate and granulate.

AM or AMF = arbuscular mycorrhiza, arbuscular mycorrhizal fungi, c.f. ECM, ERM.

amb: a general pollen shape descriptor, the outline as seen in polar view, c.f. boat-shaped, globose, oblate, prolate, spherical, terms used for the outline as seen in equatorial view.

ambo- (prefix), = both.

ambophilous: pollinated by two different classes of pollinators, e.g. by both wind and animals (insects), c.f. anemophilous, hydrophilous, zoöphilous.

ament = catkin, amentiferous = catkin-bearing.

amides: a nitrogen containing compound formed by the reaction of of an amine and a carboxylic group to form a -CONR₂ group, c.f. amines, ureide.

amines: amino acids minus their carboxyl groups, often rather smelly, c.f. amides, ureide.

amoeboid: of tapetum, where the walls break down, the protoplasts enter the anther sac, fuse, and form a syncytium (= plasmodium?) around the developing microspores or pollen, c.f. glandular and invasive.

amorphic = haplomorphic.

amphi- (prefix): both, two, complete - so rather confusing.

amphianisocytic = helicocytic.

amphibious: a plant growing both in water and on land depending on the season, etc., c.f. aquatic, epilithic, epiphytic, lithophytic, terrestrial.

amphicarpy: producing two kinds of fruit, one aerial and one subterranean (or amphi-geocarpy) on the one plant, see also geocarpy, as well as heteroanthocarpy, heterocarpidy, heterocarpy, heteromericarpy and heterospermy.

amphicribral: vascular bundles with phloem completely surrounding the xylem, c.f. amphivasal, bicollateral, collateral, also internal phloem, intraxylary phloem.

amphimixis: reproducing sexually, see androgenesis and gynogenesis (variants), c.f. apomixis s. str.

amphiphloic: of a vascular bundle that is surrounded by phloem, the xylem being in the middle, as in a dictyostele, c.f. ectophloic.

amphistomal: where the two integuments are at about the same level at the micropyle of an ovule, c.f. bistomal, endostomal, exostomal, naked, zigzag.

amphistomatic: of leaves in which stomata are borne on both sides, c.f. epistomatic and hypostomatic.

amphithecium: in bryophyte embryogeny, the outer layer of cells produced by the oblique periclinal divisions of the quadrant cells, see also endothecium.

amphitropous: of an ovule, the chalaza basal and the rest of the ovule including the embryo sac being bent as the hypostase into the main body of the ovule, the micropyle ending up next to the funicle, c.f. anatropous, atropous, campylotropous, circinotropous, hemitropous.

amphivasal: of vascular bundles, with xylem completely surrounding the phloem, c.f. amphicribral, bicollateral, collateral, also internal phloem, included phloem.

amplexicaul: of a leaf base, clasping and more or less encircling the stem yet free from it, c.f. perfoliate.

amyloid: a storage polysaccharide that stains blue, sometimes other colours, with iodine/potassium iodide solution, c.f. callose, cellulose, hemicellulose, inulin, pectin, polyol, starch.

amylopectin: a more or less coiled and branched major element of starch, insoluble in water, made up of intermediate-sized α1,4 linked glucose units that are joined to longer spacer glucans by α1,6 linkages, c.f. amylose.

amyloplast: a leucoplast in which carbohydrate is stored as starch grains, see also spiranthosome, c.f. elaioplast, proteinoplast.

amylose: a more or less coiled but essentially unbranched minor element of starch, soluble in water, made up of small alpha glucose units, the synthesis of which is associated with granule-bound starch synthase, c.f. amylopectin.

ana-: (prefix), a positional term for pollen apertures, when they are located at or towards the distal pole, distal in the context of the orientation of the grain in the tetrad, c.f. cata-, encircling, panto-, and stephano-.

anadromous: of fronds in ferns in particular, when the first lateral veins of a pinna/lobe develop acroscopically, i.e. on the side towards the apex, c.f. catadromous.

analogy: similarity between two structures because they have the same or a similar function, c.f. homology, homocracy, homoeology, paralogy, serial homology, and similarity.

anamorph: the asexual reproductive stage of a dikaryotic fungus (ascomycete, basidiomycete), often morphologically very unlike the sexually-reproducing teleomorph and like a mould; see also holomorph.

anaphoric: of distichous shoots, the lamina in bud rotated towards the upper side of the shoot, i.e. towards the parental axis of the shoot, or in spiral shoots, rotated towards the next younger leaf, so facing up the genetic spiral (Charlton 1994), seems basically the same as anodic, see also aestivation, c.f. cataphoric.

anaphyletic: a taxon made up of members which, given a particular phylogenetic network and classification based on it, include mainly the descendents of a common ancestor, but one member has hybridized with a member of a coordinate group and is included in that group and another member hybridizing with a member of another coordinate group is included here, c.f. epiphyletic, monophyletic, paraphyletic, periphyletic, polyphyletic.

anastomosis: fusion to form a network, e.g. of veins in a leaf blade.

anasulcate: of pollen grains, a common form having an elongate aperture at the distal pole of the grain, distal in the context of the orientation of the grain in the tetrad, c.f. colpate, colporate, inaperturate,omniaperturate, polyforate, pantoporate, porate, pororate, sulcate, sulculate, tenuitate, trichotomosulcate, ulcerate and zona-aperturate.

anatomy: internal structure, sometimes opposed to morphology, which is then restricted to external form.

anatropous: of an ovule, inverted 180^o so that the chalaza is apical and the micropyle is basal and faces the placenta, the body of the ovule being parallel to the funicle, c.f. amphitropous, atropous, campylotropous, circinotropous, hemitropous.

anauxotelic: applied to inflorescences, parts of inflorescences or axes that terminate in a flower, and in which growth does not continue beyond the flowering region, see also cyme, c.f. auxotelic.

ancestral: of a character, a feature of a clade more basal on the tree than that with which it is (implicitly) being contrasted, c.f. derived, c.f. also plesiomorphic.

ancipital, ancipitous = flattened and two-edged.

androdioecious: having perfect and staminate flowers on separate plants, probably very rare (most apparent examples are functionally dioecious), c.f. andromonoecious, dioecious, gynodioecious, gynomonoecious, homoecious, monoecious.

androecium: collectively the stamens of one flower, c.f. gynoecium, perianth, see diadelphous, fasciculate, monadelphous, phalangiate, syngenesious (connation, etc.), see also didynamous, tetradynamous (different lengths), heteranthy (basically different sizes), see also diplostemonous, haplostemonous, obdiplostemonous, obhaplostemonous (general arrangement), also dicycly, obmonocycly, monocycly (general arrangement, but based on putative origin, see Ronse de Craene 2010).

androgenesis: a variant of apomixis s. str. (or amphimixis, I suppose), in which a haploid male gamete in maternal cytoplasm produces an embryo, c.f. gynogenesis.

androgynophore: a receptacular stalk bearing both the androecium and gynoecium of a flower above the level of insertion of the perianth, c.f. androphore, anthophore, gynophore, stipe.

androgynous: having staminate and carpellate flowers in the same inflorescence, a variant of monoecious.

andromedotoxins: a class of diterpenes causing poisoning in animals.

Rhodojaponin VI, C20 H34 O7.

Grayanotoxin, C22 H36 O7.

andromonoecious: having perfect and staminate flowers on the same plant, c.f. androdioecious, dioecious, gynodioecious, gynomonoecious, homoecious, monoecious.

androphore: a stalk or tube bearing separate stamens at its apex, c.f. androgynophore, anthophore, gynophore, stipe.

androspore: one of the two kinds of spores produced after meiosis in an heterosporous plant and on germination giving rise to the male gametophyte, in angiosperms, a uninucleate pollen grain, see prepollen, true pollen, c.f. megaspore = microspore.

anemo- (prefix): wind.

anemochory: dispersal of diaspores by wind, c.f. atelochory, autochory, hydrochory, myrmecochory, ombrohydrochory, zoochory, see also diplochory.

anemophilous: pollinated by wind, c.f. ambophilous, hydrophilous, zoöphilous.

aneuploid: a plant with a chromosome number that is not an exact multiple of the haploid number of related plants, but is clearly similar to it, c.f. allopolyploid, agmatoploid, autopolyploid, diploid, demiduplication, dysploid, endopolyploidy, haploid, polyploid, symploid, see also mesopolyploid and palaeopolyploid

angiosperm: a seed-bearing plant with the ovules borne enclosed by a megasporophyll whose margins are variously fused, i.e., the ovules are enclosed in an ovary, c.f. gymnosperm.

angiospermy type 1: in which the carpel is occluded by secretion (see Endress & Igersheim 2000 for definitions of angiospermy types).

angiospermy type 2: in which the carpel has a continuous secretory canal, so ultimately occlusion by secretion, and there is partial postgenital fusion at the periphery.

angiospermy type 3: in which the carpel is closed by complete postgenital fusion, but there is a secretory canal that opens internally only at the inner angle of the ventral slit.

angiospermy type 4: in which the carpel is completely closed by postgenital fusion.

angle of divergence: in a genetic spiral/parastichy, the smaller angle relative to the stem circumference separating the points of origin of two successively initiated leaves, c.f. phyllotactic fraction.

angular coumarin: a fumarocoumarin in which the furan ring is at an angle to the benz-2-pyrone nucleus, as in angelicin, usually not phototoxic, c.f. linear coumarin.

angustiseptate: a fruit flattened at right angles to the septum so the septum crosses the narrowest part of the ovary, c.f. latiseptate.

anhydrobiosis: the ability of an organism to undergo essentially complete yet reversable dehydration at some stage of its life history (the plant is an anhydrobiote), see diallagyresurrection plant.

aniso- (prefix): unequal.

anisocytic: of stomata, with three subsidiary cells, two large and one smaller, surrounding the guard cells, c.f. actinocytic, allelocytic, anomocytic, cyclocytic, diacytic, helicocytic, laterocytic, paracytic, staurocytic, stephanocytic, tetracytic.

anisomerous: with an unequal number of parts in the separate whorls of a flower, although if the gynoecial whorl only differs, this may be ignored, c.f. isomerous.

anisophyllous: having leaves of very different sizes and/or shapes at the same node, c.f. heteroblastic, heterophyllous, juvenile.

anisoporous: of a plant producing two sizes of spores within the one sporangium, c.f. heterosporous, homosporous.

annual: of a life span, one that ends within one year after germination, e.g. a winter annual germinating in the autumn and flowering in the spring (esp. in Mediterranean climates), approximately synonymous to therophyte, c.f. biennial, ephemeral, perennial, c.f. also of flowering with respect to plant architecture, hapaxanthic, monocarpic, pleonanthic.

annular: arranged in or forming a ring.

annulus: in ferns, the elastic ring of more or less U-thickened cells in the sporangium wall that initiates dehiscence, forming the stomium.

annulus: an area of the exine of a pollen grain surrounding a pore.

anodic = ascending.

anomalous: a rather vague term of convenience, e.g. kinds of secondary growth that differ from the "ordinary" ones.

anomocytic: of mature stomata lacking differentiated subsidiary cells surrounding the guard cells, c.f. actinocytic, allelocytic, anisocytic, cyclocytic, diacytic, helicocytic, laterocylic, laterocytic, paracytic, parallelocytic, staurocytic, stephanocytic, tetracytic, also, in a more general classification, c.f. paracytic s.l. and stephanocytic s.l..

ante- (prefix): in front of, before, e.g. antepetalous inserted in front of (adaxially to, "opposite") the petals, antesepalous, the same for the sepals.

anterior (as used of floral organs) = abaxial, c.f. posterior.

anther: the pollen-bearing part of a stamen, with which its connective is usually described as being basifixed, centrifixed, dorsifixed, embedded, or versatile as it joins the filament, made up of a number of sporangia, in angiosperms these typically in pairs or thecae, opening by slits or ostioles, pores or valves in either the extrorse, latrorse or introrse directions , the wall often following the basic, dicotyledonous, monocotyledonous or reduced types of development, surrounding the tapetum, in turn surrounding the meiocyte, pollen, etc. (depending on the developmental stage of the male gametophyte).

antheridium: the fertile organ of a male gametophyte or the male organ of a bisexual gametophyte, in which male gametes are formed, c.f. archegonium.

antherode: the non-funational anther of a staminode.

antherozoid: a flagellated male gamete.

anthesis: the time of full opening of a flower when pollen is presented and/or the stigma is receptive.

anthocarp: a true fruit surrounded by all or just the base of the perianth, as in Nyctaginaceae and many Rosaceae-Pomoideae, really a particular kind of accessory fruit, but perhaps a term of some use, if used consistently, e.g. including fruits with persistent sepals, as in Dipterocarpaceae, see also hypocarp, c.f. aggregate fruit, multiple fruit.

anthochlors: a group of usually yellow flavonoids made up of aurones and chalcones, yellow pigments that turn red in an alkaline solution of, say ammonium, or with cigarette or cigar smoke.

anthoclade: a leafy inflorescence with extended growth and elongating internodes, looking rather like a vegetative branch.

anthocorm theory: a theory of the (parallel) evolution of the angiosperm flower from a polyaxial seed fern structure with a conspicuous main axis bearing unisexual gonoclads stubtended by bracts (Meeuse 1978), c.f. the gonophyll theory, see also phyllosporous and stachysporous.

anthocyanidins: a class of coloured anthocyanin aglycones (i.e. lacking the sugars) formed from flavan-3,4-diols, also when proanthocyanidins are hydrolyzed with acid (note that they are not formed from proanthocyanidins in the plants); major determinant of flower colour.

anthocyanins: a class of flavonoids based on the cyanidin structure, differing in the presence or absence of hydroxyl groups by methylation or glycosylation (they have sugars at position 3 and sometimes elsehwere), forming red-, pink-, purple- and blue-colored pigments, one of the two main pigment types, c.f. carotenoids.

Anthocyanin base.	Pelargonidin, C15 H11 O5.
Delphinidin, C15 H11 O7 Cl.	Cyanidin, C15 H11 O6.

anthophore: a receptacular stalk bearing the corolla, androecium and gynoecium of a flower on a stalk above the level of insertion of the calyx, c.f. androgynophore, androphore, gynophore, stipe.

anthotaxis: the arrangement of flowers along the stem, especially as they are initiated at the shoot apex, when bracts are absent, getting at the same thing as phyllotaxis.

anthotelic = determinate.

anthoxanthins: yellow, cream or colorless flavonoids occuring in cell saps.

Anthoxanthin, C21 H20 O12

anthraquinones: quinones in which the aromatic ring is fused to both sides of a benzoquinone ring, occuring as glycosides in plants, often colored.

Anthraquinone, C14 H8 O2.	Chrysophanol, C15 H10 O4.
Asphodelin, C30 H18 O8.

anti- (prefix): opposite to.

anticlinal: e.g. of cell walls, those at right angles to the surface of the organ, c.f. periclinal.

anticous: as used of floral organs, = abaxial, c.f. posticous.

antidromous: of the genetic spiral in a plant, when it changes direction along an axis, c.f. heterodromous and homodromous.

antipetalous: inserted in front of (adaxially to, "opposite") the petals.

antipodals: cells, commonly three in number as in the eight-nucleate embryo sac, located at the other end of the embryo sac from the female gamete, more or less persistent, multiplicative or not, c.f. also central cell, egg apparatus, petasus, polar nuclei, synergids.

antiraphe: on the other side of the ovule to the raphe, c.f. also chalaza, funicle, embryo sac, integument, lagenostome, megaspore, micropyle, nucellus, pollen chamber, obturator.

antirrhinoid (of a floral aestivation) descending cochleate.

antisepalous: inserted in front of (adaxially to, "opposite") the sepals.

antitropous: of the curvature of an ovule with respect to the carpel margin that bears it, curvature in the opposite direction to the curvature of the margin, i.e. the opposite direction to that of carpel closure, c.f. syntropous, see also apotropous, epitropous (lose to a synonym), pleurotropous.

antitropous: of the folding of the leaf blades of leaves on opposite sides of the stem in Marantaceae, the same side of the leaf being inrolled inside the other (actually different sides if the leaves are considered individually!), c.f. homotropous.

antrorse: bent, and pointing towards the apex, c.f. retrorse, erect.

apert = open.

aperture: a distinctly delimited part of a pollen grain in which thick intine is covered by thin exine and through which the pollen tube emerges, whether a compound or simple aperture, see colpate, inaperturate,omniaperturate, polyforate, pantoporate, colporate, porate, pororate, sulcate, sulculate, tenuitate, trichotomosulcate, ulcerate and zona-aperturate, of apertures, see also operculum, pontoperculum (covering of aperture), also ana-, cata-, encircling, panto-, and stephano- (distribution of the aperture(s) with respect to the basic polarity of the pollen grain), also ectoaperture, endoaperture, also Fisher's rule, Garside's rule (distribution of apertures), annulus and oncus (elements of apertures), and pollen buds (oddities).

apetalous: without petals, c.f. polypetalous, sympetalous.

apical: of the placentation or arrangement of the ovules in an ovary of a syncarpous gynoecium, at the top of the ovary, and hence the ovules pendulous, c.f. axile, basal, free central, laminar, marginal, parietal.

apical cell: the upper (chalazal) cell formed after the first division of the zygote, which further divides to produce the bulk of the embryo proper, c.f. basal cell.

apical hook: a hook-like structure which develops at the apical part of the of an hypocotyl in dark-grown seedlings of broad-leaved angiosperms with epigeal germination.

apical meristem: the meristem at the apex of stem or root, of which the ground meristem, intercalary meristem, procambium, protoderm can rather loosely be considered parts, c.f. lateral meristem, see root apical meristem, shoot apical meristem, also initial and morphogenetic zones (terms describing cytohistological differentiation that can be applied to all land plants), and histogens (descriptors used in an old theory of the construction of the apical meristem); see also Erstarkungswachstum.

apiculum: a short, abrupt, flexible point, adj. apiculate, but it has other meanings as well, and overall it is better replaced (along with cuspidate) by a suitably-qualified mucronate (see Rickett 1956), c.f. acumen, acute, attenuate, arista, awn, cuneate, emarginate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

apigenin: a deoxyanthocyanin occurring in leaves and flowers.

apo- (prefix): separate, c.f. syn-.

apo- (prefix): the polar region of a zonoaperturate pollen grain delimited by lines connecting the apices of the apertures, c.f. meso-.

apocarpous: of the gynoecium, consisting of two or more carpels which are initially free from one another, or a single carpel (see monomerous, but not a pseudomonomerous gynoecium), see paracarpous, coenocarpous, syncarpous.

apocole: of a monocot seedling, the elongated, usually subterranean and non-photosynthetic part of the cotyledonary hyperphyll below the haustorium and above the cotyledonary sheath, c.f. haustorium/scutellum, phanomer, see also mesocotyl, coleorhiza, hypophyll (cotyledonary sheath, coleoptile), collar (epiblast, periblast).

apogamy: of agamospermous reproduction, the asexual formation of seed, c.f. adventitious embryony, apospory, diplospory, polyembryony.

apogeotropic: of roots which grow upwards, c.f. geotropic.

apomixis: of reproduction, in the strict sense the production of viable offspring without fertilisation, equals agamospermous above (see adventitious embryony, apospory, diplospory, polyembryony), or, in a more general sense (preferred), includes the production of vegetative propagules, i.e. vegetative reproduction (for which, c.f. amphimixis).

apomorphy: of a character, derived, an evolutionary novelty arising in the immediate ancestor of a clade and characterising it, c.f. autapomorphic, plesiomorphic, synapomorphic, see also key innovation.

apomorphy-based: a way of defining a clade in which an apomorphy is the defining point, e.g. the clade stemming from the first species to possess character A (as found in a particular exemplar species), c.f. node-based, stem-based.

apopetalous = polypetalous.

apoplast: the continuum formed by the interconnected cell walls in plants, c.f. symplast.

apoptosis: programmed cell death.

aporphine alkaloids: group of isoquinoline alkaloids.

Aporphine, C17 H17 N.

aposematic: of insects, etc., with a warning colouration, perhaps because they are loaded with noxious plant secondary metabolites that they have sequestered, c.f. cryptic.

apospory: a kind of agamospermy where unreduced embryo sacs develop from ovular tissue, c.f. adventitious embryony, apogamy, diplosporypolyembryony.

apostapetalum: referring to that part of the corolla tube and lobes above the zone with fused/adnate stamens, a term of dubious utility, c.f. stapetalum.

apotact: of cochleate aestivation, the petal with its two edges outside those of the adjacent petals not immediately next to the one with the two edges both inside, c.f. ascending, descending, and paratact.

apotracheal: of axial parenchyma, parenchyma not associated with the vessels, see banded, boundary, diffuse, c.f. paratracheal (aliform, banded).

apotropous: of the curvature of an ovule with respect to the ovary axis, abaxial, c.f. epitropous, pleurotropous, see also antitropous, syntropous.

appendage: a general term for any structure that is not one of the conventional parts of an angiosperm plant that arises from the surface of another.

appendicular: of tissues or parts of the plant formed from leaves or structures considered "homologous" with them, c.f. axial.

appendicular epigyny: of epigyny, when the floral apex is initially convex, but it early flattens and a central concavity develops due to toral upgrowth of the floral cup. i.e. due to development of appendicular tissues (Kuzoff et al. 2001), c.f. receptacular epigyny.

apposition: of branching, as in the formation of a plagiotropic branching system by a series of units, each consisting of a vigorous axillary branch that is initially plagiotropic but whose apex becomes orthotropic, the terminal meristem still remaining active, as in plagiotropy by apposition as in Terminalia branching, c.f. substitution.

apposition: in cell wall formation, growth by deposition of layer after layer of wall material, c.f. intussusception.

appressed: pressed closely against a surface, often that of another organ, but not united with it, c.f. adherent, adnate, coherent, connate, connivent, fasciate, fasciculate, fastigiate, free, phalangiate.

aquatic: a plant living in or on water for all or a substantial part of the life span, c.f. amphibious, epilithic, epiphytic, epiphyllous, terrestrial.

arabinose: (C5 H9 O4)-OH - an aldopentose epimeric with ribose at the 2 carbon, occurring naturally in both D- and L-forms, widely distributed in the form of complex polysaccharides, glycosides, and mucilages; arabinoside is a glycoside of arabinose and occurs widely in plant species as a component of sugars, also in gum arabic.

arabitol: the polyol form of the preceding (an alditol), a polyol, c.f. arabitol, glycerol, mannitol, sorbitol and xylitol.

arachnoid: especially of hairs, looking rather like a tangled spider's web, c.f. arachnoid, arbuscular, canescent, hirsute, hispid, hirsute, lepidote, puberulous, pubescent, sericeous, stellate, strigose, tomentose, T-shaped, villous, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.

arborescent: of habit, resembling a tree, a term applied to non-woody plants attaining tree height and to shrubs tending to become tree-like in size, c.f. acaulescent, dendroid, frutescent, fruticose, herb, liane, rheophyte, suffrutescent, schopfbaum, shrub, subshrub, tree, vine, see also life forms.

arbuscular: hairs looking more or less stalked and branched, c.f. arachnoid, canescent, hirsute, hispid, hirsute, lepidote, puberulous, pubescent, sericeous, stellate, strigose, tomentose, T-shaped, villous, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.

arbuscular mycorrhiza: AM, an endomycorrhizal and perhaps also ectendomycorrhizal association between a fungus and a plant root where the fungal hyphae form coils and/or arbuscules (a branching, more or less tree- or shrub-like mass of fungal hyphae) or arbusculate coils within the plant cell, can be involved in mycorrhizal networks, see also Arum and Paris types, includes (in general usage) vesicular-arbuscular mycorrhizaw, c.f. ectomycorrhizae and ericoid mycorrhizae.

arbutin: a benzoquinone.

archegonial chamber: a cavity or space between the megasporangium and the female gametophyte, c.f. egg, neck, venter.

archegonium: the fertile organ of a female gametophyte or the female organ of a bisexual gametophyte of an embryophyte, in which female gametes or eggs are formed, see archegonial chamber, neck, venter, and egg, c.f. antheridium.

archesporium = tissue that gives rise to megasporocytes or microsporocytes as well as parietal tissue, including the endothecium (in the anther) and the nucellar tissue (in the ovule).

arcuate: curved like a bow.

areole: any small, discretely bounded area; a cluster of hairs/spines/bristles borne at the node of (in Cactaceae) a usually leafless stem; in Fabaceae-Caesalpinioideae-mimosoids a distinct, oblong or elliptical area on the face of a seed, bounded by a fine line, the linea fissura; in leaf venation, the space bounded by the finest veins on the lamina, adj. areolate.

aril: in the strict sense, an often fleshy outgrowth partly or wholly covering a seed and developed from the funicle or raphe, but also used more generally to refer to a similar structure derived from any part of the ovule as arillode and arilloid, adj. arillate, c.f. arillode, caruncle, coma, elaiosome, sarcotesta, strophiole. There has been much and sometimes acrimonious debate over the correct definition of the term, but it seems that "aril", rather like obturator, podium, ponticulus, postament, is best used rather broadly, with its origin being given for clarity.

arillode: not a very useful term - a fleshy structure partly or wholly covering a seed and developed from any part of the ovule, or an elaborate structure at the micropylar end of the seed (Bell & Bryan 2008), c.f. aril, caruncle, elaiosome, sarcotesta, strophiole.

arilloid: also used to refer to a fleshy structure partly or wholly covering a seed and developed from any part of the ovule, the same as aril in the broad sense, see aril s. str., arillode, caruncle, elaiosome, sarcotesta, strophiole.

arista: of the apex of a structure, having a stiff, bristle-like awn or tip, adj. aristate, c.f. acumen, acute, attenuate, apiculum, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

aristolochic acid: a phenanthrene-carboxylic acid derivative of a benzoisoquinoline precursors.

Aristolochic acid, C17 H11 N O7.

article: a segment of a jointed stem, or of a fruit with constrictions between the seeds.

articulated: jointed, e.g. the more or less swollen apex of a petiolule in particular that has a line across the broadest part, with separation commonly occuring here when the leaflets fall, articulation, c.f. pulvinus; of a stem, having prominent nodes.

articulated laticifer: of a laticifer, developing from more than one cell, unbranched or branching, anastomosing and with cross walls, c.f. non-articulated.

Arum-type arbuscular mycorrhiza: an arbuscular mycorrhizal association between a fungus and a plant root where the fungal hyphae are intercellular, and also form coils, pelotons, vesicles, and particularly branched arbuscules within the plant cell, c.f. Paris type.

arylphenalenones: phenalenones with aryl radicals, pigments found in Haemodoraceae, derived from 9-phenylphenalenone.

Haemocorin, C32 H34 O14.

ascending: growing erect after an oblique or semi-horizontal beginning, c.f. decumbent, erect, procumbent, repent, or a stem growing about 45-60° from the horizontal, c.f. orthotropic, plagiotropic.

ascending: the side of a leaf that is towards the younger leaves in the genetic spiral, c.f. descending.

ascending cochleate: cochleate aestivation in which one petal has its two edges outside those of the adjacent petals, one has its two edges both inside, and the other petals have one edge outside and the other inside, the petal with the two edges outside being in the adaxial-median position (e.g. Fabaceae-Faboideae), c.f. descending, and apotact, paratact.

ascidiate: pitcher-shaped, more or less tubular and often widening towards a flared mouth and then subpeltate, esp. used of the leaves of several carnivorous plants, see epiascidiate, hypoascidiate, or of carpels, c.f. conduplicate.

asexual (of reproduction) = apomixis s. lat., sometimes equated with vegetative reproduction.

asperulate: slightly rough to the touch.

asphodelin: a yellow colored anthraquinone.

astrosclereid: a sclereid cell with rather short, stout radiating branches, c.f. filiform sclereid, brachysclereid, macrosclereid, osteosclereid, trichosclereid.

asymmetric: with no plane of symmetry, such that dividing the structure down its axis does not produce mirror-image or identical halves, e.g. oblique leaf bases; when considering floral asymmetry, there are two main kinds, one is not very striking and is found in the haplomorphic flowers of e.g. Magnolia, where the halves are very similar, but not identical, the differences seemingly being inconsequential(!), and the other, as in Canna, is more striking, and the asymmetry, primarily in the androecium and gynoecium, is clearly connected with the pollination mechanism, see also enantiomorphic, enantiostylous, c.f. disymmetric, monosymmetric, oblique, polysymmetric.

atactostele: a stele in which the vascular bundles are scattered through the ground tissue, c.f. eustele, dictyostele, protostele, siphonostele.

atavism: a teratum that is a throwback to an ancestral condition - in the past teratology was popular in part because terata were supposed to be such throwbacks (or it was hoped that they would be).

atectate: pollen in which the sexine is represented only by isolated baculae, pilae, granules or other elements, c.f. semitectate, tectate.

atelochory: diaspores without any dispersal mechanism, c.f. anemochory, autochory, hydrochory, myrmecochory, ombrohydrochory, zoochory, see also diplochory.

atropous: a erect, straight ovule with funicle, chalaza and micropyle in a straight line, c.f. amphitropous, anatropous, campylotropous, circinotropous, hemitropous.

attenuate: tapering gradually to a point, a vague term that is probably better replaced by narrowly acute or acuminate where appropriate, c.f. acumen, acute, apiculum, arista, awn, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

aucubin: a bitter-tasting route II decarboxylated iridoid.

Aucubin, C15 H22 O9.

aulacospermous: referring to seeds in which individual endothelial cells protrude into the endosperm, the endosperm becoming alveolate (it may appear to be ruminate in cross section), c.f. bothrospermous.

aureol: a phytoalexin.

auricle: an ear-shaped appendage at the junction of leaf sheath and blade (as in grasses), or the base of a leaf, leaflet or corolla lobe, adj. auriculate.

aurones: golden-colored flavonoids isomeric with c.f. flavones with Z-sterochemistry at the double bond, often found in flowers, c.f. chalcones; they are anthochlors.

Aurone base.	Benzofuranone, C15 H10 O2.
Sulfuretin, C15 H10 O5.

autapomorphic: of a character, derived, an evolutionary novelty of a terminal clade in a particular study, at a finer level of analysis a synapomorphy of all members of that clade, c.f. also apomorphic, plesiomorphic, synapomorphic, see also key innovation.

auto- (prefix): self, alone, single.

autochory: dispersal of diaspores without the aid of any external agent, e.g. by explosive dehiscence of the fruit, c.f. anemochory, atelochory, hydrochory, myrmecochory, ombrohydrochory, zoochory, see also diplochory.

autoecious: referring to rust fungi in which the aecial and telial stages are on the one host plant, c.f. heteroecious.

autogamy: pollination and fertilisation occuring by pollen from within the same flower, c.f. allogamy, cross pollination, c.f. also geitonogamy, self pollination.

autopolyploid: a plant with a chromosome number that is a multiple of base number (n) of its parent, hybridisation not being involved, represented as 3x, 4x, etc., c.f. allopolyploid, aneuploid, agmatoploid, diploid, demiduplication, dysploid, endopolyploidy, haploid, polyploid, symploid, see also mesopolyploid and palaeopolyploid

autotroph: an organism independent of others in respect of organic nutrition, being able to fix carbon dioxide by photosynthesis, to form carbohydrates, c.f. biotroph, hemiparasite, heterotroph, hyperparasite, mixotroph, myco-heterotroph, parasite, saprobe/saprophyte/saprotroph.

autumn wood = late wood.

auxoblast = long shoot.

auxotelic: applied to inflorescences, parts of inflorescences or to axes that do not end in a flower, and in which growth continues beyond the flowering region, c.f. anauxotelic, see also raceme.

awn: of the apex of a structure, a long bristle-like appendage, e.g. on the tip or back of the lemma or other spikelet part of a grass, c.f. acute, attenuate, acumen, apiculum, arista, cuneate, caudate, cuspidate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate, c.f. also cordate, hastate, oblique, runcinate, sagittate (esp. of lamina base).

axicorn: tissue on the inside of the fruit of Campanulaceae-Campanuloideae which moves as it dries and perforates the fruit wall, so allowing the dispersal of the seeds.

axial: of tissues or parts of the plant formed from stem (or root) or structures considered "homologous" with them, c.f. appendicular.

axial bundle: a major vascular bundle of a sympodium, c.f. leaf gap, leaf trace.

axial parenchyma: longitudinally-elongated parenchyma cells in among the tracheary tissue, see aliform, apotracheal, banded and paratracheal, c.f. ray parenchyma.

axicorn: a structure involved in the dehiscence of some caspsules which on drying causes holes, flaps, or slits to appear in the walls.

axil: the angle formed by an axis and a leaf borne on it, it, adj. axillary.

axile: of the placentation or arrangement of the ovules in an ovary of a syncarpous gynoecium (inapplicable if the gynoecium is pseudomonomerous), with septae separating loculi, the ovules being borne on the central axis, c.f. apical, basal (these two really just variants of axile placentation), free central, laminar, marginal, parietal.

axillary bud/branch: a bud (or buds) or branch in the axil of a leaf that subtends it, c.f. serial, number of buds, c.f. leaf-opposed, subpetiolar, supra-axillary., position of buds, also dichotomous, type of branching, also cauliflorous, ramiflorous, terminal, of inflorescence or infructescence position, also concaulescent, epicaulescent, see recaulescent, variants of axillary branching.

axis: a stem, the term being commonly used for the main stem of a plant or of an inflorescence, see inflorescence axis.

azetidine-2-carboxylic acid: C4 H7 N O2, a non-protein amino acid, an alpha-amino acid with a primary -imino group (-NH) and a carboxyl group attached to the same carbon atom.

B

baccate: berry-like, not strictly a berry, or the adjectival form of berry.

baculum (Erdtman term): in pollen, a cylindrical, free standing element of exine/sexine element more than 1µm in length and less than this in diameter (baculae, baculate), c.f. columella, and because a baculum supports nothing, it is an element of pollen ornamentation, c.f. also echinate, fossulate, gemmate, foveolate, pilate, lophate, metareticulate, psilate, reticulate, retipilate, rugulate, scabrate, striate, verrucose.

banded: of axial parenchyma, the parenchyma cells forming bands, whether or not associated with vessels, i.e. either apotracheal, c.f. boundary, diffuse, or paratracheal, c.f. aliform.

banner: of a petal = standard.

barbed: terminal or lateral retrorse projections on a structure, each projection being a barb, c.f. glochidiate; barbellae, short, straight, stiff hairs or barbs, adj. barbellate.

bark: a non-technical term for that part of the stem or root outside the vascular cambium, see inner bark, outer bark.

bars of Sanio: two bar-like thickenings (crassulae) made up largely of primary cell wall material that are found on either side of a bordered pit.

basal: at the base; of the placentation or arrangement of the ovules in an ovary of a syncarpous gynoecium, the ovules then usually ascending or erect, c.f. apical, axile, free-central, intrusive-parietal, laminar, marginal, parietal.

basal cell: the basal, i.e. micropylar, cell formed after the first division of the zygote, which further divides to produce the suspensor, cf apical cell.

basal cell: the basal, i.e. micropylar, cell of the suspensor in the proembryo, often enlarged or even haustorial, c.f. hypophysis, also the lowermost cell formed after the first division of the zygote, which further divides to produce the suspensor, cf apical cell.

basal leaves: the leaves at the base of the stem, c.f. also rosette leaves, c.f. cauline.

base number: the haploid chromosome number of the common ancestor of a group, represented as "x" followed by the actual number.

base plate: the inner periclinal wall of an endothecial cell bearing a more or less plate-like and lignified thickening, coming in a variety of forms (see Manning 1996).

basic: anther wall development in which the primary parietal layer gives rise to two secondary parietal layers, the outer producing the endothecium and middle layer, the inner producing cells of the middle layer and tapetum, c.f. dicotyledonous, monocotyledonous, reduced.

basifixed: attached at or by the base, e.g. of anthers, attached by the base to the filament, c.f. centrifixed, dorsifixed, embedded, versatile.

basifugal = acropetal.

basinerved = palmate.

basipetal: produced or differentiated in succession towards the base of an organ, e.g. of an inflorescence, with flowers arising or developing in a sequence beginning at the apex and proceeding towards the base, see also centrifugal, c.f. acropetal.

basiplastic: of development, when the apex of a leaf primordium becomes mature early, "stretching"/elongation proceeding from the tip to a basal meristem (Foster 1952), c.f. basiplastic, pleuroplastic, see also eocladous.

basiscopic = retrorse.

basitonic: a branching pattern in which the basal buds of a season's growth/innovation grow out most strongly, as in Trema, c.f. acrotonic, mesotonic.

bast: the portion of the inner bark represented by the phloem.

beak: a prominent terminal projection, especially of a carpel or fruit.

bee purple: in mellitophily or bee pollination, the color of yellow ultra-violet reflecting flowers; since bees can see in the ultraviolet, the combination is a very distinctive color. Yellow flowers that absorb in the ultraviolet appear pure yellow to the bee.

begonioid: a leaf tooth in which there is a translucent apical pad of densely packed cells, one lateral vein strengthened at the expense of the apical and the other lateral vein, perhaps a close to a cucurbitoid tooth, c.f. also chloranthoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, theoid, urticoid, violoid.

Beltian body: a protein-rich multicellular food body produced at the ends of the leaflets of some species of Acacia subgenus Acacia (= Vachellia), "swollen thorn acacias", c.f. colleter (perhaps), Müllerian body, pearl gland, and snail gland.

benzene: an aromatic 6-carbon ring.

Benzene, C6 H6.

benzofuran: a type of terpene formed from dimethylallyl pyrophosphate and an acetate-derived polyketide precursor.

Base structure.

benzoisoquinolines: organic compounds where the benzene ring added to an isoquinoline nucleus.

benzopyran: a type of terpene, pigments, a class of chromone.

Benzopyran, C9 H8 O.

benzoquinones: simple quinones in which an aromatic ring is fused to two oxygen atoms, there being two carbonyl groups, usually in the para (1,4) position; often yellow in color.

Benzoquinone base.	Arbutin, C12 H16 O7.
Embelin, C17 H26 O4.	Maesaquinone, C26 H42 O4.

benzylisoquinoline alkaloids: a group of isoquinoline alkaloids, usually poisonous; modified dimers of tyrosine derived from 3.4-dihydroxytyramine (dopamine) condensed with a carbonyl compound (4-hydroxyphenylacetaldehyde), a benzene ring added to an isoquinoline nucleus.

Miltanthaline, C21 H28 N O4.

berberine: a benzylisoquinoline alkaloid.

berry: strictly speaking, a usually fleshy or pulpy indehiscent fruit s. str. with the seed(s) surrounded by the more or less fleshy tissue of the pericarp, adj. baccate, c.f. drupe, used more generally, any dispersal structure that consists of fleshy tissue surrounding seeds, as in blueberry (Vaccinium spp.) or small, hard dispersal units in general, as in the blackberry (Rubus spp. - pyrenes), or bearing such units on the surface, as in the strawberry (Fragaria spp. - achenes).

betacyanins: red-violet betalains.

beta-carbaline alkaloids: a class of indole alkaloids which are derived from the amino acid L-tryptophan.

Beta-carbaline base.	Methoxyharmalan, C13 H14 N2 O.
Harmine, C13 H12 N2 O.

betaines: alkaloid-like compound, a quaternary ammonium basic derivative, may play a role in osmotic regulation in halophytes.

Betaine, C5 H11 N O2.

Homobetaine, C6 H13 N O2.

betalains: type of alkaloid, a chromalkaloid (coloured alkaloid); although not really anthocyanins, they are often called "nitrogenous anthocyanins", including betacyanins and betaxanthins.

Betanine, C24 H26 N2 O13.

betaxanthins: yellow betalains.

bi- (prefix): two, having two of anything, sometimes (and confusingly), two different things, for which the prefix "hetero" is preferable.

bicollateral: of vascular bundles with phloem on both abaxial and adaxial sides, c.f. amphicribral, amphivasal, collateral, also internal phloem, intraxylary phloem.

bicolor unit: a unit of the inflorescence in many Malvaceae consisting of a modified cyme with three bracts on the peduncle and a terminal flower, two bracts subtending ± ordinary cymose branches, sometimes the whole reduced to a single flower and an epicalyx, the latter deing derived from the three bracts, c.f. cyathium, see dichasia and monochasia (basic types), and drepanium, helicoid cyme, rhipidium, scorpioid cyme (variants).

biennial: of a life span, a plant which lives for more than one but less than two years after germination, c.f. annual, ephemeral, perennial, of flowering with respect to plant architecture, hapaxanthic, monocarpic, pleonanthic.

bifacial: of flattened structures, especially leaves, having distinct adaxial and abaxial surfaces, see dorsiventral, isobifacial, c.f. unifacial.

bifid: forked or divided for about half the length of the structure, or into two parts, c.f. bipartite.

biflavonoids: class of flavonoids, most of which are flavone and flavanone dimers with a simple 5, 7-4'- or 5,7,3',4'-oxygenation pattern, derived from the oxidative coupling of two chalcone units and subsequent modification of the central C3 units.

Amentoflavone, C30 H18 O10.

biflavonyls: a class of flavonoids formed by the dimerization of the flavone apigenin.

Kayaflavone, C33 H24 O10.

bifoliolate: of leaves, having two leaflets.

biforine: raphide-containing cells that have thickened, lignified walls, but usually with thin-walled papillae at the end through which raphides are quickly extruded when the side walls are deformed, the "defensive raphide cells" of some.

bigeminate: in two pairs.

bijugate: of leaves and other lateral organs; in opposite pairs, the pairs being not quite at right angles to each other, c.f. alternate, decussate, distichous, geminate, opposite, pseudoverticillate, spiral, spiromonistichous, tristichous, whorled.

bilabiate: two-lipped, e.g. of a monosymmetric flower in which the corolla has distinct adaxial and abaxial lobes surrounding the mouth, see also personate, c.f. papilionoid, slit-monosymmetric.

bilateral (of symmetry) when loosely used, = monosymmetric, strictly speaking, = disymmetric.

bilocular: having two cavities.

binate: borne in pairs, e.g. the two leaflets of some compound leaves.

binucleate: of pollen grains in which the male gametophyte has two nuclei when shed from the anther, c.f. trinucleate.

biomass: a rather vague term, the mass of living organisms in a particular area, possibly including microroganisms associated with the organisms of interest, and the mass measured in various ways, living tissues, dried or not, net primary productivity, etc., c.f. necromass.

biome: global biotic units in which the vegetation has a similar physiognomy (Eiserhardt et al. 2017), c.f. community.

biotroph: a plant with a variant of heterotrophic nutrition in which the organism obtains its carbon via symbiotic interactions with its host organism, as in mycorrhizal associations, c.f. autotroph, hemiparasite, hyperparasite, mixotroph, myco-heterotroph, parasite, saprobe/saprophyte/saprotroph.

biotroph: a parasite that derives its nutrition from the living cells of its host, c.f. necrotroph.

bipartite: divided, nearly to the base, into two parts, c.f. bifid.

bipinnate: of compound leaves, twice pinnately divided, c.f. pinnate.

biradial (of symmetry) = disymmetric.

biseriate: arranged in two rows or whorls, especially of the perianth and androecium.

biserrate: of the margin of a leaf, with larger and smaller asymmetrical forwardly-pointing teeth more or less regularly arranged, c.f. crenate, dentate, entire, serrate, sinuate, undulate.

bisexual (of flowers) = perfect.

bistomal: where the micropyle of an ovule is formed from both integuments, c.f. amphistomal, endostomal, exostomal, naked, zigzag.

bizonoplast: a modified chloroplast found in e.g. some species of Selaginella, large and cup-shaped and with an upper zone that has many layers of 2–4 stacked thylakoid membranes and a lower zone that has both unstacked stromal thylakoids and thylakoid lamellae stacked in normal grana structure and variously oriented (e.g. see Sheue et al. American J. Bot. 94: 1922. 2007), c.f. chloroplast, chromoplast, iridoplast, leucoplast, sieve tube plastid.

BLA: broad-leaved angiosperms, in old textbooks called dicotyledons, c.f. monocotyledons.

blade (of leaf) = lamina.

blastotelic = indeterminate.

blastozone, see marginal blastozone.

boat-shaped: a general pollen shape descriptor, a grain in which the polar axis is short and one equatorial axis is longer than the other, i.e. the grain is boat-shaped, c.f. globose and its variants, oblate, prolate, spherical.

bole: the trunk of a tree below the lowest branch, c.f. crown.

border cells: cells of the root cap that have separated from it, although remaining attached because they are enclosed in a layer of sticky mucilage, c.f. columella, peripheral root cap.

bordered: a pit in which the pit membrane is overarched by the secondary wall, so forming a border, see margo, bars of Sanio, torus, c.f. scalariform, simple, vestured.

bostryx = helicoid cyme.

bothrospermous: referring to seeds in which the inpushings of individual endothelial cells into the endosperm become confluent in vertical rows, the endosperm becoming more or less alveolate or ruminate in crosss section, c.f. aulacospermous.

botryoid: a raceme with a terminal flower, c.f. also capitulum, corymb, fascicle, spadix, spike, thyrse, umbel.

boundary: of apotracheal parenchyma, parenchyma occuring at the beginning or end of a growth period, c.f. banded, diffuse.

brachy- (prefix): short, c.f. dolicho-.

brachyblast = short shoot.

brachyparacytic: of paracytic stomata, with two subsidiary cells parallel to the guard cells but not entirely enveloping them, c.f. laterocylic.

brachysclereid: a sclereid cell about as long as broad, lacking processes, a stone cell, c.f. astrosclereid, filiform sclereid, macrosclereid, osteosclereid, trichosclereid.

bract: a leaf, usually different in form from the foliage leaves, subtending a flower, quite often called a floral bract, c.f. bracteole, inflorescence bract.

bracteole: a small leaf or leaves borne singly or two together and more or less opposite on the pedicel, the prophyll(s) of the flower-shoot (pedicel plus flower), c.f. bract.

bractlet: a vague term, referring either to a small bract, to a floral prophyll or bracteole, or to some other small inflorescence bract, etc.

bradyspory: the enclosure of seeds in a more or less massive woody covering that provides physical protection against seed-eaters and fire, often associated with serotiny.

branching: see axillary, dichotomous, also concaulescent, epicaulescent, and recaulescent, and also acrotonic, basitonic, mesotonic.

broad(ly): a qualifier of terms used for outlines and plane shapes when the length:breadth ratio is 4:3 - 1:1, c.f. broad-transverse, narrowly, transverse, the terms qualified being elliptic, obovate, oblong, ovate, rhombic, triangular, trullate.

broad-transverse: a qualifier of terms used for outlines and plane shapes when the length:breadth ratio is 1:1 - 4:5, c.f. broadly, narrowly, transverse, the terms qualified being elliptic, obovate, oblong, ovate, rhombic, triangular, trullate.

brochi, sing. brochus: of pollen grains, a lumen in the reticulum of the tectum and half the width of the adjacent muri.

brochidodromous: of leaf venation, pinnate venation (camptodromous in particular) in which the secondary veins do not terminate at the margins but are joined in a series of prominent arches, c.f. eucamptodromous, reticulodromous in particular, c.f. also acrodromous, actinodromous, campylodromous, cladodromous, craspedodromous, dichotomous, flabellate, parallelodromous, semicraspedodromous, simple-craspedodromous.

brown rot: fungal wood degradation in which cellulose, including crystalline cellulose, is selectively targeted, facilitated by the non-enzymatic modification of lignin, but without the lignin being broken down, common under conifers, c.f. soft rot and white rot.

brush presentation: a type of secondary pollen presentation in which the pollen in presented to the pollinator entangled in a mass of hairs, c.f. pump presentation.

bud: any stem meristem - vegetative or floral - in an embryonic stage, whether resting or not and whether protected by bud scales or not, see neoformation and preformation, prolepsis and syllepsis, adventitiousbud and preventitious, and epicormic and sequential, all different aspects of the timing of bud growth, also naked, perulate, aspects of the protection of buds, axillary, subpetiolar, supra-axillary, position of the buds, and see serial, number of buds.

bud scale: a scale leaf more or less surrounding a perulate resting bud, c.f. naked bud.

bufadienolides: a group of cardiac glycosides with a six-membered lactone ring with two double bonds at C17, act as heart poisons and toxins, c.f. cardenolides.

Bufadienolide, C24 H38 O2.

bulb: a storage organ, usually underground, made up of a relatively inconspicuous stem and large leaf bases, the food reserves being stored in the inner, fleshy leaf bases, see hysteranthous, proteranthous and synanthous (flowering relative to leaf production), c.f. bulbil, caudex, corm, culm, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tendril, tuber, turion.

bulbil: a small, deciduous "bulb", i.e. a rounded structure of variable construction, formed in the axil of a leaf or replacing flowers in an inflorescence, and functioning to propagate the plant vegetatively, a.k.a. "aerial vegetative diaspore", see bulbil s. str., cormlet, gemma and tubercle (see Zona & Howard 2021), c.f. bulb, caudex, corm, culm, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tendril, tuber, turion.

bulbil sensu stricto: aerial vegetative diaspore consisting of scale leaves, c.f. cormlet, gemma and tubercle.

bullate: having a blistered or puckered surface, e.g. of a leaf surface, prominently raised (almost like a subcutaneous bubble) between veins.

bulliform cells: large thin-walled epidermal cells that often occur in bands down the leaf, especially in monocots, c.f. stomata, neighbour cells, pavement cells

bundle: often short for vascular bundle, often visible as a bundle scar marking the course of a vascular bundle in the outer cortex and evident when the leaf falls from the stem; the number of bundle scars allows one to infer (sometimes incorrectly!) the number of leaf traces and hence aspects of nodal anatomy, also bundle cap, sclerenchyma or collenchyma that forms a cap on either/both the adaxial and abaxial sides of a vascular bundle, bundle sheath, distinctive cells that entirely surround the vascular bundle, see mestome sheath, parenchyma sheath, starch sheath.

bundle compound: a compound leaf in which "the arrangement of the leaflets on the petiole apex [is] similar to that of flowers in an umbel" (Grushvitzky & Skvortsova 1970: p. 536), as in some Araliaceae, see also pinnate, palmate and pedate.

bundle sheath: the tissue surrounding a vascular bundle, see embedded and transcurrent.

burr: a rough or prickly propagule consisting of a seed or fruit and associated floral parts or bracts.

buttress: a vertical flange of tissue protruding from the base of the trunk of a tree or where a leaf joins the stem.

buzz pollination: a variant of mellitophily where the bee vibrates a pendulous flower (its own wing muscles vibrate) causing the pollen to fall out of the anthers, the bee then collecting it; the flowers are polysymmetrical, the anthers often form a cone, and the petals are also reflexed, i.e. a very different floral morphology from that of many bee-pollinated flowers.

C

C₃ photosynthesis: a photosynthetic pathway typically occuring entirely during daylight hours and involving the fixation of CO₂ initially as a 3-C compound in the Calvin cycle (C3 photosynthesis), c.f. C₄, CAM, CAM cycling and LPP.

C₄ photosynthesis: a photosynthetic pathway typically occuring entirely during daylight hours and involving the fixation of CO₂ initially as a 4-C compound spatially separated from cells/organelles to which the 4-C compound is moved and then broken down and where the final product of the whole processs is a 3-C compound produced by the Calvin cycle (C3 photosynthesis), c.f. C₃, CAM, CAM cycling and LPP.

C-value: a measure of nuclear genome size, the amount of DNA in the unreplicated nucleus, measured in picograms.

1C-value: a measure of nuclear genome size, the amount of DNA in the haploid nuclear genome; in flowering plant genome broken up as follows: [very small] <1.4 pg - [small]- 3.5 pg - [intermediate] - 14.0 pg - [large] 35< pg [very large] (Soltis et al. 2003c).

1Cx-value: a measure of nuclear genome size, the amount of DNA in the basic monoploid chromosome set.

2C-value: a measure of nuclear genome size, the amount of DNA in the nucleus in the sporophytic or somatic phase, see also EI.

CAM: a photosynthetic pathway in which stomata are closed during the day and open during the night, carbon being fixed in the dark as 4C compounds (e.g. malic acid) by phosphoenolpyruvate, these later being broken down releasing CO₂ and carbon entering the plant's metabolic cycles as the 3C compound 3-phosphoglycerate, c.f. C3, C4, and CAM cycling.

CAM cycling: a photosynthetic pathway in which stomata do not entirely close during the day and the CO₂ entering the plant's metabolic cycles comes from recycling of respiratory CO₂, c.f. C3, C4, and CAM.

cabbage tree = schopfbaum.

caducous: esp. of the calyx and/or corolla, falling off early compared to those of other plants, but not withering (e.g. the calyx of Papaver), c.f. accrescent, deciduous, deliquescent, fugacious, marcescent, persistent.

caesalpinioid: a type of nodule caused by nitrogen-fixing bacteria in Fabaceae, more or less perennial, with a sub-apical growing point, elongate, terete and sometimes branched, lacking lenticels, and with a narrow point of attachment, c.f. aeschynomenoid, crotalarioid, desmodioid, and lupin type.

caespitose: growing in tufts.

caffeic acid: a phenol formed from cinnamic acid, more frequently occurs as an ester, as in chlorogenic acid, c.f. ferulic acid, p-coumaric acid, sinapic acid.

Caffeic acid, C9 H8 O4.

Caffeic acid ester, C17 H13 O6.

caffeine: a pseudoalkaloid.

calcar, calcarate = spur, spurred.

calcium oxalate: the common constituent of crystals in plant cells or their walls, found either as crystal sand, druses, prisms, raphides, or styloids.

Calcium oxalate, Ca C2 H2 O4.

callose: a polymer of glucose, a ß-(1→3) linked glucan, found especially in the area of the sieve plate in sieve elements, also in the pollen tube, etc., c.f. amyloid, cellulose, hemicellulose, inulin, pectin, polyol, starch.

callose ring: a callosic stucture that surrounds the microsporocyte at the beginning of meiosis, whether or not persisting later (Sannier et al. 2007).

callus: an unorganised, proliferative mass of large more or less thin-walled cells that are often formed after an injury, but are sometimes a regular feature of the plant and then used to refer to more or less soft excrescences developing from the surface, e.g. on the labellum of some orchids and on the axis of the spikelet of some grasses; they may function in disarticulation of a floret or spikelet, as in grasses, or attarct ants, pl. calli.

calycanthemous: "having sepals wholly or partly converted into petals" - umph!

calycine: pertaining to the calyx.

calycophyll: when the calyx is more or less expanded and like a petal/petals, as in some Rubiaceae (functionally, it may also be a fruit wing); see also watercalyx.

calyculus: a structure varying in its morphological nature that is borne on the outside of and looks like a small calyx, see in particular epicalyx.

calymmate: of a pollen tetrad or polyad, when the ectexine is not separately differentiated on each grain, but forms a common covering for the pollen mass, c.f. acalymmate.

calyptra: in general, any cap-shaped structure on top of something else.

calyptra: in a "bryophyte", a cap-like structure covering or partly covering the sporangium/capsule and derived from the venter of the archegonium sporangium, see also columella, operculum, peristome, seta, stomium.

calyptra: in a flower = operculum, the calyx and corolla fused together.

calyx: the sepals of one flower collectively, see also calycophyll, watercalyx, c.f. androecium, corolla, gynoecium, perianth.

calyx tube: a tube formed by connation of the sepals alone, the calyx limb being the total length of the structure and the calyx lobes the free parts of the sepals at the end.

cambial initials: actively-dividing cambial cells in either cork or vascular cambia that by periclinal divisions produce cells both to the outside and inside, see fusiform initials, ray initials.

cambium: pl. cambia, lateral meristems made up of undifferentiated cells whose products are arranged in radial files and cause secondary thickening, see cork cambium, vascular cambium, see also master cambium, polyderm, see also initial.

campanulate: e.g. of a polysymmetric corolla, bell-shaped, broadly tubular and then gradually widening towards the more or less spreading lobes, c.f. rotate, infundibular, salverform, tubular, urceolate.

camptodromous: of leaf venation, pinnate venation in which the secondary veins do not terminate at the margins, includes brochidodromous, eucamptodromous, reticulodromous, c.f. acrodromous, actinodromous, campylodromous, cladodromous, craspedodromous, dichotomous, flabellate, palmate, parallelodromous, semicraspedodromous, simple-craspedodromous.

campylodromous: of leaf venation, more or less parallel venation in which the veins originate at the base and run in incurved arches before converging at the leaf apex, c.f. parallelodromous, c.f. also acrodromous, actinodromous, brochidodromous, camptodromous, cladodromous, craspedodromous, dichotomous, eucamptodromous, flabellate, reticulodromous, semicraspedodromous, simple-craspedodromous.

campylotropous: of an ovule, orientated transversely with its axis at right angles to its funicle and with a curved embryo sac, the micropyle being close to the funicle, c.f. amphitropous, anatropous, atropous, circinotropous, hemitropous.

canaliculate: with a longitudinal groove or channel.

canescent: more or less shortly grey-pubescent, hoary, c.f. arachnoid, arbuscular, hirsute, hispid, hirsute, lepidote, puberulous, pubescent, sericeous, stellate, strigose, tomentose, T-shaped, villous, see also glabrescent and glabrate, which refer to stages in the loss of these hairs.

canopy: the branches and foliage of a plant, ± irrespective of its size, c.f. bole.

cantharophilous: a variant of entomophilous pollination in which the flowers are pollinated by beetles, c.f. melittophilous , myophilous, phalaenophilous, psychophilous, sapromyophilous, sphigophilous.

capillary: of hairs etc., very slender.

capitate: e.g. of a stigma, head-like, globose, like the head of a pin, c.f. clavate.

capitulum: an inflorescence with sessile flowers aggregated into a dense cluster, whether a racemose (more usual) or cymose, sometimes made up of disc and ray flowers, c.f. botryoid, corymb, fascicle, raceme, spike, thyrse, umbel.

capreolate = tendrillate.

capsule: in an angiosperm, a usually dry fruit formed from two or more united carpels and dehiscing at maturity to release the seeds, sometimes with valves, see circumscissile, loculicidal, poricidal, septicidal, septifragal (variants), see also follicle (when fruit is a single carpel), schizocarp (when fruit breaks up into single-seeded units, arguably a variant of septicidal dehiscence), and axicorn (a particular structure involved in fruit dehiscence).

capsule: in a "bryophyte" = the sporangium, see calyptra, columella, operculum, peristome, seta, stomium.

caput: of a pollen grain, an architectural element on top of a columella, discontinuous and not confluent (see tectum), c.f. baculum, intectate.

carbohydrates: aldehydes or ketones with many hydroxyl groups added, either occuring as single molecules or variously linked, see monosaccharides, disaccharides, oligosaccharides, polysaccharides.

carboxylate: the carboxylate anion is an ion with a negative charge that contains the group -COO^-, the base of a carboxylic acid, e.g. tricarboxylic citrates and dicarboxylic malates formed from citric and malic acids respectively.

carboxylated iridoids: a kind of route II iridoid (= normal route II) derived from epi-iridodial and epi-iridotrial via glucosylation and oxidation of C₁₁ to the carboxyl level, c.f. decarboxylated iridoids.

Strictoloside, C16 H22 O12.

Ipolamiide, C17 H26 O11.

carboxylic acid: organic acids which have one or more carboxyl (-COOH) groups, see citric and malic acids.

cardenolides: cardiac glycosides with a five-membered lactone ring attached at C17, inc. heart poisons and toxins, taken up by monarch and danaid butterflies, also some aphids, c.f. bufadienolides.

Cardenolide, C23 H36 O2.

cardiac glycosides: a group of compounds with a steroid nucleus, a sugar at C 3 (hence the glycoside part), and a lactone at C-17, see bufadienolides, cardenolides, c.f. cyanogenic glycosides, glucosinolates (types of glycosides).

carinal canal: parenchyma-surrounded spaces in a vascular bundle, perhaps caused by cells breaking down or separating as later-developing tissue expands, sometimes also called a protoxylem lacuna.

carinate = keeled, with a median ridge or fold on the abaxial surface of the structure, in particular, carinate aestivation of caesalpinioid Fabaceae, where the keel petals enclose the rest, a variant of cochleate or imbricate aestivation; the carina of the flower of some Fabaceae = keel.

carnose = fleshy.

carotenoids: subclass of fat-soluble terpenes that consist of two diterpene phytol-like units (C40 compounds, 8 isoprene units), the most familiar tetraterpenoids forming one of the two main groups of plant pigments and occurring as yellow, orange or red carotenes and xanthophylls, c.f. anthocyanins.

Lutein, C40 H56 O2.

carpel: megasporophyll, a unit of the gynoecium, usually two or more in number and almost always at the centre of a flower, more or less tubular and their margins more or less fused together (see ascidiate, conduplicate, angiospermy type 1, etc.) and/or with other carpels (see syncarpous, also mixomerous, monomerous and pseudomonomerous) to enclose the ovule(s), and made up of an ovary, stigma and usually a style, or a gynoecial appendage that encloses but does not necessarily bear ovules - Sattler and Perlin (1982).

carpellate: (e.g. of a flower) with functional carpels only, c.f. neuter, perfect, staminate.

carpellode: a non-functional carpel, c.f. pistillode.

carpidiophore: a persistent woody fruit base of a capsule or schizocarp.

carpophore: the central axis that persists between the carpels in a schizocarp where the ovary is inferior, e.g. remaining after the mericarps are shed in Apiaceae, c.f. columella.

carpopodium: a term used by synantherologists to refer to the basal abscission zone of the cypsela/achene and consisting of one or two rows of cells that are distinct morphologically from other cells of the cypselal wall.

caruncle: a more or less fleshy (often hard) outgrowth from the surface of a seed, usually near the micropyle, c.f. aril, arillode, coma, elaiosome, strophiole.

caryophyllaceous (of stomata) = diacytic.

caryopsis: a dry, indehiscent, one-seeded fruit in which the seed coat is closely fused to the fruit wall, a variant of an achene s. str.; characteristic of grasses, other taxa also have the pericarp fused to the testa, c.f. cypsela, nut, utricle.

Casparian band: a waxy band-like formation within primary walls that contains lignin and suberin located in the anticlinal walls, especially in endodermis, see also exodermis.

castanospermine: a polyhydroxy alkaloid.

casuarinine: a polyhydroxy alkaloid.

cata-: (prefix), a positional term for pollen grains, of a feature at the proximal pole of the grain (for apertures, this position would be decidedly uncommon), proximal in the context of the orientation of the grain in the tetrad, i.e. in the centre of the tetrad, c.f. ana-, encircling, panto- and stephano-.

catadromous: of fronds in ferns in particular, when the first lateral veins of a pinna/lobe develop basiscopically, i.e. on the side towards the base, c.f. anadromous.

catalepsis = prolepsis.

catalpol: a route II iridoid.

cataphyll: a modified, reduced and more or less non-photosynthetic leaf, found e.g. on vegetatively propagating organs such as a rhizome or perennating bud, or near the base of the innovation, sometimes the first leaves on a seedling, probably can be replaced by scale leaf or bud scale, c.f. also hypsophyll, perula.

cataphoric: of distichous shoots, the lamina in bud rotated towards the lower side of the shoot, i.e. away from the parental axis of the shoot, or in spiral shoots, rotated towards the next older leaf, so facing down the genetic spiral (Charlton 1994), see also aestivation, c.f. anaphoric. Seems basically the same as cathodic.

catechol: a phenolic compound, i.a. the probable precursor of phytomelan.

cathodic = descendingl.

catkin: a dense spike-like inflorescence, often with cymose branches, in which the flowers are imperfect and lack a perianth (or the perianth is inconspicuous), finally deciduous as a whole.

caudate: of an appendage at the apex of a leaf, etc. - narrow, rather flexible, terminal and tail-like, c.f. acumen, acute, apiculate, attenuate, arista, awn, cuspidate, cuneate, emarginate, mucronate, muticous, obtuse, retuse, rounded, truncate.

caudex: a ± short, thick, erect trunk or stem, somewhat above to somewhat below ground level, c.f. bulb, bulbil, corm, culm, dropper, lignotuber, pseudobulb, rhizome, runner, stolon, tendril, tuber, turion.

cauduciform: a plant with an enlarged, swollen, usually water-storing basal portion of the stem.

caudicula/caudicle: in Orchidaceae, a stout to slender and more or less elastic structure derived from inside the anther, the pollinia are attached at one end and the viscidium at the other - for other commonly-used terms specific to orchid flowers, see column, hamulus, incumbent, labellum, rostellum, massulae, sectile, stipes, tegula, also epichile, hypochile. A similar structure in Apocynaceae is called the translator.

cauliflorous: with flowers (and fruits) borne on a well-developed trunk or major branch, commonly used to describe general inflorescence position, c.f. axillary, leaf-opposed, ramiflorous, supra-axillary, terminal.

cauline: e.g. describing leaves borne on an aerial stem, usually separated by elongated internodes, c.f. basal and rosette leaves ; of flowers or fruits, see cauliflorous.

caulome: a collective term for all stems of a plant and their modifications, c.f. hadrom(e), leptom(e), phyllome, polysaccharide.

caulomere = sympodial unit.

caulonema: part of the gametophytic protonema made up of longer and narrower cells with few plastids and involved in substrate colonization and nutrient uptake, the cell plate being oblique to the long axis of the cell, c.f. chloronema.

caveate: a term for all pollen in which the columellae in the regions between the apertures become separated from the foot layer, i.e. it as if the foot layer had split periclinally.

cavitation: the arupt formation of air bubbles by embolism in vessels and tracheids, so blocking water flow, c.f. root pressure.

cecidium = gall.

cell: the basic unit of plant (and animal) structure consisting of a unit bounded by a plasma membrane, generally containing a single nucleus, c.f. protoplast, c.f. also organ, tissue. The cell is surrounded by a wall which, it can be argued, is not part of the cell proper, although some botanical definitions in particular suggest that it is, the "cell" then including the extracellular matrix of the wall and bounded by the middle lamella. Although the narrower definition of cell may be useful in broadly comparative biological discussion, the ubiquity of the wall surrounding plant cells cannot be ignored, and also the fact that it is synthesised at the plasma membrane, and that vacuoles are also surrounded by a plasma membrane (and are therefore extracellular?!). In any event, when mention is made of the "cells" of the spongy mesophyll, or when the inner integument is described as being eight "cells" across, it may be assumed that walls are included as part of the mesophyll and integument respectively... (c.f. Robinson 1991, Sack 1991).

cell: when referring to anthers ("anthers 2-celled"), better to use sporangium/ia or theca(e).

cellular: of endosperm formation, where all nuclear divisions of the endosperm are accompanied by cell wall formation, c.f. helobial, nuclear.

cellulose: a more or less straight polysaccharide chain formed by hundreds of ßglucose molecules, a major component of the plant cell wall, c.f. amyloid, callose, hemicellulose, inulin, pectin, polyol, starch.

cell wall storage polysaccharides: polysaccharides in the plant cell wall that serve as storage compounds, see galactans, mannans, and xyloglucans.

central cell: the large cell initially usually containing two nuclei (polar nuclei) that makes up the bulk of the eight-nucleate embryo sac, see also antipodals, egg cell, synergids.

central pollen grains: condition where there is a relatively large number of pollen grains in the anther sporangium and in no particular arangement,many of the grains not being in contact with the tapetum, c.f. peripheral pollen grains.

centrifixed: the filament joining the anther in such a way that the anther surrounds the filament at the point of attachment, perhaps a variant of basifixed, c.f. basifixed, dorsifixed, embedded, versatile.

centrifugal: directed, or developing, from the centre or axis outwards, c.f. centripetal, see also basipetal, endarch (of xylem development).

centripetal: directed, or developing, from the outside towards the centre or axis, c.f. centrifugal, see also acropetal, exarch (of xylem development).

centromere: site on the chromosome where spindle fibers attach during nuclear division, see acrocentric, holocentric, metacentric, and telocentric.

cephalium: in Cactaceae, a flowering area at the apex of the stem - sometimes only on one side - with confluent areoles that have more hairs and/or spines than other areoles, the area having a thick periderm underneath so the stem is not photosynthetic.

ceratolin: a dihydrochalcone.

C-glucosyl- or C-glycosyl-: of e.g. flavonoids in which linkage of a carbon-carbon bond involves the anomeric carbon of the sugar and position 6, 8, or both, of a flavone (vertical bond on left-hand side between the benzene ring and the sugar), difficult to hydrolyse, c.f. O-glycosyl.

Maysin, C27 H28 O14.

chaffy: of texture, thin and membranous, c.f. chartaceous, coriaceous, papyraceous, scarious; chaff, the bracts subtending flowers in some Asteraceae, or the glumes, etc., of some fruiting Poaceae.

chalaza: that part of an ovule to which the end of the funicle is attached and below the insertion of the integuments, c.f. also antiraphe, embryo sac, lagenostome, megaspore, micropyle, nucellus, pollen chamber, obturator, podium, ponticulus, postament, raphe.

chalazal cyst: a more or less sac-like part of the endosperm at the chalazal end surrounded by transfer cells and involved in the transfer of nutrients to the developing seed, c.f. primary endosperm nucleus, perisperm.

chalazogamy: fertilisation during which the pollen tube penetrates the ovule by way of the chalaza, c.f. mesogamy, porogamy, pseudoporogamy.

chalazosperm: nutritive tissue in a seed, developed from persistent chalazal cells, c.f. chalazal cyst, endosperm, primary endosperm nucleus, perisperm.

chalcones: intermediates in the production of all flavonoids, but rarely accumulated, isomeric with flavanones, the A ring being derived from acetate and with a phloroglucinol oxidation pattern, the B ring from a phenylpropanoid precursor, and with an allyl bridge (-CH:CH.CO) separating the two rings, yellow in colour and most often found in flowers, c.f. chalcones; they are anthochlors.

Chalcone base.

Isosalipurposide, C21 H22 O10.

chamaephyte: of life forms, plants with resting buds between ground level and 25cm, c.f. cryptophyte (geophyte, hemicryptophyte, hydrophyte), helophyte, phanerophyte, therophyte.

chambered: of pith which is divided into separate compartments, usually by septae made up of sclerified cells.

character: any feature of the organism, see character state (the two are sometimes used interchangeably), polarization.

character state: a division of a character, e.g. ovary, superior versus inferior.

chartaceous: papery in texture, c.f. coriaceous, papyraceous, scarious.

chasmogamous: flowers that open and are pollinated then, c.f. cleistogamous.

chelidonic acid: an organic acid derived from a condensation of C3 and C4 units related to phosphoenolpyruvic acid and erythrose-4-phosphate.

Chelidonic acid, C7 H4 O6.

chicle: a component of latex, made up of isoprene units, trans and cis 1,4-polyisoprenes, E and Z polyisoprene, c.f. gutta, rubber.

chim(a)era: tissue derived from two (or even more) individuals, as in a graft hybrid.

chiropterophilous: a kind of zoöphilous pollination, flowers pollinated by bats, with a distinctive morphological syndrome (e.g. dull color; robust; presented so access is easy), ornithophilous.

-chlamydeous (part of a compound): from the greek, a covering, a set of structures.

chlamydospermous: chlamydospermous seeds have a thin single integument prolonged into a long micropyle/beak, the whole surrounded by a thick layer derived from bract/s.

chloranthoid: a leaf tooth with a clear persistent swollen cap, medial secondary or tertiary vein accompanied by (1)2 higher-order laterals that enter the apex or fuse with the medial, c.f. begonioid, cucurbitoid, cunonioid, dillenioid, malvoid, monimioid, platanoid, rosoid, salicoid, spinose, theoid, urticoid, violoid.

chlorogenic acid: type of phenylpropanoid involving cinnamic acid derivatives; a depside of caffeic acid linked to quinic acid, c.f. rosmarinic acid.

Chlorogenic acid, C16 H18 O9.

chloronema: part of the gametophytic protonema made up of rather broader cells with numerous plastids and involved in photosynthesis, the cell plate being transverse to the long axis of the cell, c.f. caulonema.

chloroplast: a cell organelle surrounded by two double membranes that originated by endosymbiosis and now is involved in photosynthesis , containing circular DNA (part of the plant genome), a kind of plastid, including grana, pyrenoids, thylakoids, c.f. amyloplast, bizonoplast, chromoplast, iridoplast, leucoplast, sieve tube plastid.

-chorous, -chory, -chore (suffix), refers to the dispersal syndrome/mechanism of seed or fruit.

choripetalous = polypetalous.

chorisepalous = polysepalous.

chroman ring:

Chroman ring, C9 H10 O.

chromoalkaloids = betalains.

chromones: a type of coumarin consisting of a benzene ring fused to a pyrone ring with a methyl group at the C2 position and oxygenated at the C5 and C7 positions.

Chromone, C9 H6 O2.

chromoplast: a plastid with abundant yellow or orange carotenoids, c.f. bizonoplast, chloroplast, iridoplast, leucoplast, sieve tube plastid.

chromosome: a thread-like structure in the nucleus or chloroplasts of a cell, containing a linear sequence of genes, see centromere, also karyotype, see also allopolyploid, aneuploid, autopolyploid, diploid, demiduplication, dysploid, endopolyploidy, haploid, polyploid.

chrysophanol: an anthraquinone.

cincinnus = scorpioid cyme.

cinereous: ash-grey, as of wood ash.

cinnamic acid: a simple phenol derived from L-phenylalanine, involved in formation of phenylpropanoids, occurring in various aromatic resins; common hydroxycinnamic acids are caffeic acid, ferulic acid, p-coumaric acid, sinapic acid; depsides include chlorogenic acid and rosmarinic acid.

Cinnamic acid, C9 H8 O2.

circinate: of leaf vernation, the lamina is spirally coiled downwards from the apex, with the tip innermost, c.f. conduplicate, conduplicate-flat, conduplicate-involute, conduplicate-plicate, curved, flat, involute, plicate, revolute, supervolute, supervolute-curved, supervolute-involute.

circinotropous: of an ovule, with a long funicle curved so that the ovule is held upside-down, c.f. amphitropous, anatropous, atropous, campylotropous, hemitropous.

circumscissile: esp. of capsules, breaking open along a transverse line around the circumference, c.f. loculicidal, poricidal, septicidal, septifragal. (includes operculate in the image).

cirrus = tendril, see also cirrhose, cirrhous, cirrhus, cirriferous, cirrose, and cirrous!

citric acid: a carboxylic acid with the formula HOOC-CH₂-COH(COOH)-CH₂-COOH, c.f. malic acid.

clade: any monophyletic group of organisms, c.f. grade, see lineage, also apomorphy-based, node-based, stem-based (ways of naming), also crown group, stem group (parts of clade), and also in group, outgroup, sister group.

cladode: a flattened, more or less leaf-like but indeterminate photosynthetic stem of a plant whose normal leaves are much reduced, c.f. phyllode, phylloclade.

cladodromous: of venation where the secondary veins are dendritic, branching freely towards the margin, c.f. acrodromous, brochidodromous, campylodromous, craspedodromous, dichotomous, eucamptodromous, flabellate, parallelodromous, semicraspedodromous, simple-craspedodromous

cladophyll = cladode.

cladoptosis: loss of whole branches or branchlets by abscission at the base, c.f. deciduous.

class: a rank in the taxonomic hierarchy with the termination -ales, a group of orders that is hypothesised to be monophyletic, placed in a division/phylum, c.f. family, genus, species.

clathrate: latticed or pierced with apertures like a trellis.

clavate: club-shaped, rather gradually widening towards the apex, c.f. capitate, of elements of pollen sculpturing, = pilate.

claw: a sharply narrowed and stalk-like basal portion of a petal, sepal or bract, c.f. limb.

cleavage polyembryony: where more than one embryo per ovule develops because of the subdivision and separation of several embryos from one proembryo, c.f. adventitious (poly)embryony, simple polyembryony.

cleistogamous: flowers that never open but are self-pollinated and set fertile seed, c.f. chasmogamous; the term recalcitrant may be used here, but is not recommended.

clockwise: of the direction of twining, the stem taking an ascending clockwise course when viewed from above, or of the genetic spiral, the course the spiral takes when going from older to younger leaves when viewed from above, c.f. counterclockwise.

clone: a set of organisms produced from one parent by vegetative reproduction.

closed: of a root apical meristem in which one or more tissue regions of the root can be traced to separate initials, c.f. intermediate meristem, open meristem.

closed: of an inflorescence in which the axis terminates in a flower, even if buds along the axis below grow out before themselves terminating in flowers, c.f. open inflorescence, c.f. also determinate, sympodial.

closed: of minor vein phloem anatomy where there are <10 plasmodesmata/mm² between bundle sheath and companion cells, movement of photosynthesate probably being apoplastic, c.f. open.

closed: of a leaf sheath, one which forms an uninterrupted cylinder around the stem, c.f. open.

closed: of a vascular bundle in which all the cells differentiate, c.f. open.

closed: of the stem vascular system in which the sympodia are linked, there being fusion between vascular bundles, so that a reticulating vascular system results, c.f. open, intermediate.

closed: of leaf venation, = reticulate, c.f. open.

cocarcinogenins: phorbol ester diterpenes, a type of carcinogen that promotes neoplastic growth only after its initiation by another substance.

coccus = mericarp.

cochleate, cochlear: coiled like a snail-shell; of imbricate aestivation, one petal with both its edges outside those of the adjacent petals, one with the two edges both inside, and the other petals with one edge outside and the other inside, see ascending, descending, and apotact, paratact, c.f. contorted, contortiplicate, crumpled, decussate, quincuncial. (imbricate in the image)

coenocarpous = syncarpous s.l., i.e. including syncarpous s. str. and paracarpous.

coenocyte: a cell in which the nuclei divide, but not the cytoplasm, resulting in a cell containing several nuclei, see also plasmodium, syncytium.

coflorescence: the cluster of flowers that terminates a lateral branch of a synflorescence, c.f. enrichment zone, florescence, paraclade, c.f. inflorescence.

coherent: floral parts of the same kind that are stuck together, but without organic fusion, n. cohesion, c.f. adherent, adnate, appressed, connate, connivent, fasciate, fasciculate, fastigiate, phalangiate.

coleoptile: a tubular structure (a ligule) developed at the apex of a closed cotyledonary sheath and surrounding the plumule of a monocot embryo or seedling, see also mesocotyl, coleorhiza, hyperphyll (apocole, scutellum, phanomer), hypophyll (cotyledonary sheath, coleoptile), collar (epiblast, periblast), the set of terms applied to monocot seedlings.

coleorhiza: tissue initially entirely surrounding and latterly forming a collar around the base of shoot-born roots on a young seedling axis of some monocots, or an annular ± sheathing structure at the base of the hypocotyl in some Myrtaceae, see also mesocotyl, coleorhiza, hyperphyll (apocole, scutellum, phanomer), hypophyll (cotyledonary sheath, coleoptile), collar (epiblast, periblast), the set of terms applied to monocot seedlings.

collar: where base of the hypocotyl, sometimes marked by an external line, a swollen area, and/or bearing collar rhizoids, and the radicle in the embryo or seedling come together, see epiblast, periblast, also cotyledon, eophyll, epicotyl, mesocotyl, plumule, primary leaf, of a monocot seedling, see also mesocotyl, coleorhiza, hyperphyll (apocole, haustorium/scutellum, phanomer), hypophyll (cotyledonary sheath, coleoptile).

collar rhizoids - see rhizoids.

collateral: of serial axillary buds, carpels, or ovules, situated side by side, and therefore not on the same radius, c.f. superposed.

collateral: of vascular bundles, with phloem on the abaxial side only (the common condition), c.f. amphicribral, amphivasal, bicollateral, c.f. also internal phloem, intraxylary phloem.

collenchyma: mechanical tissue, the cells are often elongated, their walls may be heavily thickened at the angles and are made up of pectic and cellulosic material, c.f. aerenchyma, parenchyma, sclerenchyma.

collet = collar.

colleter: often obviously mucilaginous secretory hair, not often vascularised, commonly found in groups or tufts near or at the adaxial base of the leaf and calyx, c.f. collar rhizoid, dendritic, malpighiaceous, stellate, T-shaped hair, c.f. also (perhaps) Beltian body, Müllerian body, pearl gland, snail gland.

collinearity: similar arrangement of genes in two taxa established by an empirical comparison of gene order, c.f. collar rhizoid, synteny.

colpate (adj., n. = colpus, sing. colpi, pl): of pollen grains, having elongate vertical/longitudinal apertures with a length:width ratio >2:1, c.f. anasulcate, colporate, inaperturate,omniaperturate, polyforate, pantoporate, porate, pororate, sulcate, sulculate, tenuitate, trichotomosulcate, ulcerate and zona-aperturate.

colporate: of pollen grains, having elongate compound apertures with a length:width ratio >2:1 (colpi) and inside that more or less circular apertures (pori), c.f. anasulcate, colpate, inaperturate,omniaperturate, polyforate, pantoporate, porate, pororate, sulcate, sulculate, tenuitate, trichotomosulcate, ulcerate and zona-aperturate..

columella: literally "a little column", the central, persistent axis of a capsular fruit derived from a superior ovary, c.f. carpophore.

columella: in a "bryophyte", central sterile tissue in the sporangium/capsule, see also calyptra, operculum, peristome, seta, stomium.

columella: cells of the root cap that are derived from an independent set of initials and which are involved in gravity sensing, c.f. border cells, peripheral root cap, and protoderm.

columellae: of a pollen grain, rod-like elements of the infratectum of the ectexine, supporting either the tectum or a caput, hence columellate pollen, c.f. alveolate and granulate, c.f. also baculum, intectate.

column: the lower, twisted part of a geniculate awn, or that part of a branched awn below the branching point; in grasses.

column: in Orchidaceae (and Stylidiaceae) a structure extending above the ovary and incorporating stigma, style and stamens, = gynostemium - for other commonly-used terms specific to orchid flowers, see caudicula, hamulus, incumbent, labellum, rostellum, massulae, sectile, stipes, tegula, viscidium, also epichile, hypochile.

coma: a tuft of hairs at one end of a seed, adj. comose, c.f. aril, caruncle, elaiosome, strophiole, c.f. also plumose.

commissure: a joint or seam, e.g. the interface of two fused carpels of an ovary or two petals of a corolla, used as a positional term, e.g. commissural stigma.

community: interacting populations of two or more species in a particular geographical area at the same time, either groups of species or all the species there, c.f. biome.

companion cell: a cell in phloem tissue of angiosperms, elongated, nucleate, metabolically very active and derived from the same mother cell that produces the closely associated sieve tube, intermediary cells and transfer cells are variants, c.f. albuminous cell.