Hybosema

Taxonomy

Hybosema H.A.T. Harms Repert. Spec. Nov. Regni Veg. 19: 66. 31 Mai 1923.

Subfamily: Faboideae.
Phylogenetic Number: 3.8.04.
Tribe: Robinieae.
Group: Gliricidia.
Species Studied - Species in Genus: 2 studied; 2 in genus.

Description

Fruit: A legume; unilocular; 4–17 cm long; 0.7–2.2 cm wide; 2–9 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; not plicate; not twisted; symmetrical, or asymmetrical; oblong (linear), or linear (broadly); with both sutures nearly straight; not inflated; flattened; without beak; short tapered at apex; aligned with longitudinal axis of fruit; long tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; margin not constricted; margin without sulcus; margin plain; nonstipitate; 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); with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous. Endocarp present; visible; dull; opaque; monochrome; tan; spongy; without adhering pieces of testa; septate, or nonseptate; with septa thicker than paper, firm; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 4–5; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; triangular; straight. Aril present; dry; when dry tongue-aril; entire; brown (reddish), or tan.

Seed: 5–10 mm long; 5–7.5 mm wide; 1–2.3 mm thick; not overgrown; not angular; asymmetrical; circular (sub), or ovate; flattened, or compressed (nearly flattened); with surface smooth; without visible 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; brown (dark reddish); glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from hilum to lens; not bifurcating; color of testa, or darker than testa; brown (reddish); recessed. Hilum present; partially concealed; concealed by aril; 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; recessed; within rim; rim color of testa. Lens discernible; with margins curved; elliptic; not in groove of raphe; adjacent to hilum; 1 mm from hilum; mounded; similar color as testa; not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa. Cotyledons smooth; both outer faces convex; both the same thickness; both more or less of equal length; not folded; 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; brown (dark 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; bulbose; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed; glabrous.

Distribution

South and east Mexico and northern Central America.

New World; southern and eastern Mexico to Central America.

Generic Notes

Sousa and Lavin (1992) named a new species, and our species count includes their new species. Lavin and Sousa (1995) monographed Hybosema. We believe that our studied seeds were all immature, hence the lower measurements for seed length, width, and thickness. Likely the upper measurements are the accurate ones for mature seeds.

Tribal Notes

Tribe Robinieae

The genera, generic groups, and related data follow the tribal treatment of Lavin and Sousa (1995; Polhill, 1994a, 1994b), not Polhill and Sousa (1981).