Hymenostegia

Taxonomy

Hymenostegia (G. Bentham) H.A.T. Harms In Engler & Prantl, Nat. Pflanzenfam. Nachtr. 193. Oct 1897.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.4.10.
Tribe: Detarieae.
Group: Hymenostegia.
Species Studied - Species in Genus: 5 studied; 16 in genus.

Description

Fruit: A legume; unilocular; 7–11 cm long; 3- 3.3–4.5 cm wide; 0.3–0.7 cm thick; length less than twice as long as width to 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; with 1 straight and 1 curved suture; widest near middle or D-shaped, or widest near apex (stated as "scimitar-shaped"); not inflated; compressed; without beak; tapered at apex; aligned with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit to oblique 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; wing(s) absent; stipitate to substipitate; with the stipe 6–12 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; active; with valves separately enrolling, or breaking (or both, "fracturing transversely"). Replum invisible. Epicarp dull; monochrome; yellowish tan to brown; with surface texture uniform; glabrous; eglandular; without spines; smooth, or not smooth; with elevated features; veined; transversely veined relative to fruit length; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; ligneous. Endocarp present; visible; dull; opaque; monochrome; tan; without adhering pieces of testa; nonseptate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 2–3; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–2 mm long; of 1 length only; flattened; straight. Aril absent.

Seed: 18–25 mm long; 13–20 mm wide; 4–8 mm thick; not overgrown; not angular; symmetrical; circular to oblong; compressed; 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, or mottled; dark and light reddish brown; with brown overlay; glabrous; not smooth; with elevated features, or recessed features; rugose; pitted with small separate pits (or not pitted); coriaceous to chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; without faboid split; larger than punctiform; 0.1–1.5 mm long; with curved outline; elliptic; apical at apex of radicle tip; raised to flush; not within corona, halo, or rim. Lens not discernible. Endosperm absent. 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; partially concealing radicle (only tip exposed), or completely concealing radicle; split over radicle and notched at radicle; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Gulf of Guinea.

Old World; Africa (Gulf of Guinea).

Tribal Notes

Tribe Detarieae

Bruneau et al. (2000) carried out extensive phylogenetic analyses of tribes Amherstieae and Detarieae. They concluded that they form a single monophyletic group. Therefore, they supported Polhill's (1995a, 1995b) decision to unite the two tribes.