Subfamily: Faboideae.
Phylogenetic Number: 3.8.08.
Tribe: Robinieae.
Group: Robinia.
Species Studied - Species in Genus: 19 studied; 39 in genus.
Fruit: A legume; unilocular; 1–17 cm long; 0.2–1.1 cm wide; 0.1–0.15 cm thick; 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx; without orifice formed by curving of fruit or fruit segments; straight, or curved (or slightly curved); not plicate; not twisted; symmetrical, or asymmetrical; linear, or oblong (linear), or falcate; with both sutures nearly straight; not inflated; flattened, or compressed; without beak; tapered at apex, or short tapered at apex; aligned with longitudinal axis of fruit; tapered at base, or short tapered at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; seed chambers with the raised seed chambers torulose, or not torulose; margin constricted, or not constricted; margin constricted along both margins, or slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; stipitate, or substipitate, or nonstipitate; with the stipe 0.1–20 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves twisting. Replum invisible. Epicarp dull; monochrome; brown (reddish to greenish); with surface texture uniform; glabrous, or pubescent and indurate; with hairs erect; with 1 type of pubescence, or 2 types of pubescence (glandular and nonglandular hairs); puberulent, or tomentose, or villous, or sericeous; with pubescence gray, or golden; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular, or glandular; with glandular hairs; without spines, or with spines (rarely); not smooth; with elevated features; not veined; not tuberculate; rugose, or warty, or wrinkled; not exfoliating, or exfoliating in part; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin, or thick, or trace; surface not veined; 1-layered; with balsamic vesicles; without fibers; without reniform canals; solid, or mealy (reddish-brown); coriaceous, or chartaceous. Endocarp present; visible; glossy; opaque; monochrome; tan (to grayish), or gray; smooth, or scurfy (large segments), or fibrous; without adhering pieces of testa; septate (false septa according to Lavin, 1988), or nonseptate; with septa thicker than paper, firm; with septa eglandular; coriaceous, or chartaceous; not exfoliating; separating with mesocarp from epicarp (traces of mesocarp tissue remaining adnate to both epicarp and endocarp); without wings; entire. Seed(s) 1–30; length parallel with fruit length, or transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; thick; straight. Aril present, or absent (may remain with funiculus in fruit); dry; when dry rim-aril, or tongue-aril; entire; tan.
Seed: 1.5–7 mm long; 1.5–7 mm wide; 0.5–1.7 mm thick; not overgrown; not angular, or angular; asymmetrical; circular (more or less), or D-shaped, or ovate, or quadrangular, or rectangular; compressed; with surface smooth; without visible radicle and cotyledon lobes, or with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; without hilar sinus; without umbo on seed faces; without medial ridge on each face. Cuticle not exfoliating; not inflated; not wrinkled. Testa present; without pieces of adhering epicarp; not adhering to endocarp; free from endocarp; dull; not modified by a bloom; colored; monochrome, or mottled; with frequent mottles; brown (reddish), or black, or gray; with black overlay, or purple overlay; glabrous; smooth, or not smooth; with elevated features; tuberculate, or warty; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim present. Wing(s) absent. Raphe visible; from hilum through lens to base of seed and terminating, or hilum to lens, or hilum through lens and base of seed to point opposite hilum; not bifurcating; darker than testa; brown (reddish); flush. Hilum present; partially concealed, or visible; concealed by funicular remnant; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; apical at apex of radicle tip, or subapical to radicle tip; recessed (barely); within rim, or within halo; halo lighter than testa; rim color of testa, or lighter than testa. Lens discernible, or not discernible; with margins straight, or curved; triangular; circular, or elliptic; not in groove of raphe; adjacent to hilum, or confluent with hilum; 0.1–1 mm from hilum; flush, or mounded (to barely so), or recessed; same color as testa, or similar color as testa, or dissimilar color from testa; darker than testa; brown (reddish); not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa, or embryo. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded, or with only 1 folded; not sufficiently folded for inner face to touch itself; portions of inner folded face unequal; margin entire 180 degrees from base of radicle; similar at apex; not concealing radicle; split over radicle; with lobes; without basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; tan (to greenish or reddish); inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear, or bulbose (somewhat); lobe tip straight; deflexed and parallel to cotyledon length; centered between cotyledons; less than 1/2 length of cotyledons, or 1/2 to nearly length of cotyledons. Plumule rudimentary, or moderately developed; glabrous.
Lavin (1987) included Cracca, Neocracca, and Poissonia in Coursetia, and these genera were recognized by Polhill and Sousa (1981). Lavin (1988) monographed Coursetia and his species count is used, not that of Polhill and Sousa. He (Lavin, 1988) used the outline of the fruit's seed compartment as one key character for separating sections Madrenses, Poissonia, and Coursetia from sections Neocracca and Craccoides. The former three sections have rounded seed compartments, and the latter two have squarish seed compartments. He also noted that unlike other genera in the Robinieae, the seeds are in compartments formed "by the lateral adhesion of the inner epidermis of each valve between seeds." In figure 8 of Lavin, the endocarps of the valves touch, without fusing, to form the seed compartments. Where the endocarps touch each other they are functional septa.
Authors: J.H. Kirkbride, Jr., C.R. Gunn, A.L. Weitzman, M.J. Dallwitz, K.R. Thiele
Content last updated April 2003
Released April 2024 on idtools.org
