Dichrostachys

Taxonomy

Dichrostachys (A.P. de Candolle) R. Wight & G.A.W. Arnott Nom. cons. Prodr. 271. Oct (prim.) 1834.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.32.
Tribe: Mimoseae.
Group: Dichrostachys.
Species Studied - Species in Genus: 3 studied; ca. 17 in genus.

Description

Fruit: A legume; unilocular; 2–10 cm long; 0.4–3.5 cm wide; 0.2–0.8 cm thick; 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; curved to 1-coiled (undulate and contorted); not plicate; twisted, or not twisted; symmetrical, or asymmetrical; broadly linear to linear, or reniform; with both sutures unequally curved; not inflated; compressed; without beak; rounded at apex; oblique with longitudinal axis of fruit; rounded at base to short tapered at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally visible; margin constricted to not constricted; margin slightly constricted along both margins, or slightly constricted only on 1 margin; margin without sulcus; margin plain; wing(s) absent; nonstipitate; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves active; with valves irregularly breaking (from sutures or remaining attached to sutures). Replum invisible. Epicarp glossy; monochrome; brown to red (blackish); with surface texture uniform; pubescent and indurate (when young), or glabrate (when becoming older), or glabrous; with hairs erect; with simple hairs; eglandular; without spines; smooth, or not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; nonseptate; not exfoliating; entire. Seed(s) 4–8; length oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 2.5–2.7 mm long; of 1 length only; filiform; coiled. Aril absent.

Seed: 4–6 mm long; 3–4.5 mm wide; 1–2.3 mm thick; not overgrown; not angular; symmetrical; elliptic to ovate, or 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; glossy to dull; not modified by a bloom; colored; monochrome; brown; glabrous; smooth, or not smooth; with recessed features; minutely pitted with small separate pits; coriaceous. Pleurogram present; 75 %. Pseudopleurogram absent. Fracture lines present, or absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; without faboid split; punctiform; subapical to radicle tip; recessed; not within corona, halo, or rim. Lens not discernible, or discernible; when discernable 0.2–0.3 mm long; with margins straight, or curved; triangular; elliptic, or circular; not in groove of raphe; flush to mounded, or recessed (pit, surrounded by tan and/or darker brown patch or patch absent); same color as testa, or similar color as testa; lighter than testa, or darker than testa; tan to brown (dark); not within corona, halo, or rim. Endosperm present; thin to thick; not pluglike and not resembling tip of radicle; adnate to testa. Cotyledons smooth; both outer faces flat; 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; with lobes; with lobes touching (auriculate); without basal groin formed by lobes; 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; straight with embryonic axis; centered between cotyledons. Plumule moderately developed; glabrous.

Distribution

Generic Notes

Also see notes for Gagnebina, 3.35, and Alantsilodendron, 3.35a. Fruits of D. cinera subsp. platycarpa may be dimorphic. One type shown in D was found on two specimens, and the other type shown in (E) is not a complete fruit and resembles the other Dichrostachys fruits. Brenan in Brenan and Brummitt (1965) and in personal communication, 1982, considered D. cinerea, D. glomerata (Forsskal) Chiovenda, and D. platycarpa to be 1 species wiith 10 subspecies and D. cinerea to be the correct name for this complex. Du Puy et al. (2002) added five more endemic Madagascarian species to the genus. Fruits of the Afriican taxa are indehiscent.