A Grammatical Dictionary of Botanical Latin

Labellum, 'a little lip;' “the third petal of an Orchid, usually turned towards the lower frontof the flower, and very different in form from the remainder; also a similar petal in other flowers” (Lindley); “the characteristic upper (but by a twist of the pedicel apparently lower) petal of the Orchidaceae” (Fernald 1950); in a tripetalous orchidaceous flower, the third petal when it is different from the other two by relative shape, size or color. It is usually the lower (abaxial) petal of the three: labellum,-i (s.n.II), abl. sg. labello, nom.& acc. pl. labella, dat.& abl. pl. labellis [> L. dim. of labrum,-i (s.n.III) a lip]; see hypochilium, epichilium, mesochilium;

- labellum orbiculare flabellatum vel ellipticum apice excisum 2-3 mm. latum multinervosum basi ante ostium callo instructum, labellum orbicular fan-shaped or elliptic at the tip cut out (notched) 2-3 mm broad many-nerved at base in front of the opening with a thickening provided

- labellum ex ungue brevissimo ambitu ovatum obscure quadrilobatum, lobulis lateralibus quam intermediis majoribus, omnibus rotundatis, labellum from a very short claw in outline ovate obscurely four-lobed, with the lateral lobules than the middle ones larger, all of them rounded (Stearn 1983).

- petalum inferam seu labellum violaceum ungue albido, lateralia violacea , superiora alba (DeCandolle), the lower petal or labellum violet with a whitish claw, the lateral [petals] violet, the upper ones white.

- apertura [i.e. opening] magna inferne labello munita (DeCandolle), with the aperture large, armed below with a [little] lip.

- labello calyce multo longiore (DeCandolle), with the labellum much longer than the calyx.

- labello cuneato-spathulato emarginato (DeCandolle), with the labellum cuneate-spathulate, emarginate [i.e. notched].

- labello calyce duplo triplove longiore stipitato (DeCandolle), with the labellum twice- or triple times longer than the calyx, stalked.

- labelli limbo subrhomboideo (DeCandolle), with the limb of the labellum somewhat rhomboidal.

- labello obovato basi gibboso extus pubescente (DeCandolle), with the labellum obovate, gibbous at the base, externally pubescent.

- labello spathulato apice rotundato calycem superante (DeCandolle), with the labellum spathulate, rounded at the apex, over-topping the calyx.

- labello longe unguiculato latissime ovato acuto basi dilatato flavo maculato concavo (DeCandolle), with the labellum long unquiculate very broadly ovate, acute, dilated yellow spotted concave at the base.

- labello calycem triplo superante ovato bilobo, lobis rotundatis patentibus, (DeCandolle), with the labellum three times over-topping the calyx, ovate, bilobed, with the lobes rounded, spreading.

- [Burmanniaceae] In tribù Corsicarum perianthii segmentum unum maximum primo aspectu labellum Orchìdearum in mentem revocat, sed ad seriem exteriorem pertinet nec ut in Orchideis e segmento interiore cum staminodio verisimiliter confluente sistens (B&H), at first sight the one very large segment of the perianth in the tribe Corsicae, recalls in the mind the labellum of Orchideae, but it it belongs to the outer series, not as in Orchideae, being likely from an interior segment confluent with the staminode.