A Grammatical Dictionary of Botanical Latin

Costa, midrib; often used to indicate a nerve or vein; “the midrib of a leaf; that part which is a direct extension of the petiole, and whence the veins arise; a leaf may have many costae” (Lindley); “a rib, when single, a midrib or middle-nerve” (Jackson); (bryophytes) “nerve or midrib of a leaf, always more than one cell thick” (Magill 1990); (fungi) “a ridge or rib” (S&D): costa,-ae (s.f.I), abl. sg. costa, nom. pl. costae, acc.pl. costas, dat. & abl.pl. costis [> L. costa,-ae (s.f.I), a rib = Gk. pleuron, a rib; in Gk. comp. = pleur-, pleuro-, q.v.]; (in liverworts), see vitta; see rib;

Vitta,-ae (s.f.I), q.v.: the vitta of Diatoms “are longitudinal ribs” (Jackson).

- folia nervo ad summum apicem attingente instructa (Hooker), leaves provided with a nerve (costa) attaining to the highest tip of the apex.

- costa in sectione transversali e strato medio cellularum magnarum composita, costa in cross section composed of a middle layer of large cells.

- costa sub apice evanescens, midrib vanishing before reaching the apex.

- nervo valido flavido stricto in mucronem brevissimum attenuato, with a strong nerve yellowish straight abbreviated into a very short mucro.

- costa in apiculum validum acutum laevem rubrum excurrens, costa excurrent into an apiculus robust sharp smooth red.

- costa supra medium folii soluta, costa above the middle of the leaf dissapeared.

- costa sub apice evanida, costa disappearing below the apex.

- costa subpercurrens, in foliis superioris in subula evanida, costa subpercurrent, in the upper leaves disappearing into a subula.

- costa laminas in mucronem transludicum excedente, with the costa rising above the laminas into a translucid mucro.

- [Victoria; a genus] folia natantia, maxima, supra corrugato-bullata, punctis pertusa, subtus costis insigniter prominentibus reticulata (B&H), leaves floating, very large, on top corrugate-bullate [i.e. coarsely wrinkled and with blister-like projections], pierced through with punctures [i.e. small holes], beneath reticulate with strikingly prominent ribs [i.e. veins].

[four generic names:] Acosta,-ae (s.f.I), ‘lacking a rib, midrib or costa] (Asteraceae; Ericaceae; Polygalaceae; Hypnaceae).

Costa,-ae (s.f.I): (in diatoms) “an unornamented, elongated thickening of the valve. Costa usually refers to a thickening parallel to the striae.... Morphogenetically, a costa parallel to the striae is a secondarily thickened virga. An axial costa is an internal, narrow ridge of silica positioned along the axial area” (DNA; Diatoms of North Ameria). Costa,-ae (s.f.I) longitudinalis (adj.B), abl. sg. costa longitudinali: longitudinal costa; in Diatoms, the pseudoraphe, q.v.

Vitta, q.v.: (in bryology) “a band or ribbon; in liverworts the longitudinal stripe of longer, often thicker-walled cells in a leaf lamina resembling a nerve but only one cell layer thick; e.g. Herbertus” (Magill 1990): vitta,-ae (s.f.I).

NOTE: “Nerve: used for principal or more conspicuous unbranched veins starting from the midrib or base of the blade, as distinguished from those which divide or branch and are termed veins or veinlets: nervus,-i (s.m.II); nervus secundarius (adj.A), also nervus lateralis (adj.B), ‘secondary nerve;’ the midrib being nervus medius (adj.A) (Stearn).