Xeroderris

Taxonomy

Xeroderris G.E. Roberty Bull. Inst. Franc. Afr. Noire Sér. A. 16: 353. Apr 1954.

Subfamily: Faboideae.
Phylogenetic Number: 3.7.
Tribe: Millettieae.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 10–13.5 cm long; 3–4.2 cm wide; 0.6–0.9 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; not plicate; not twisted; symmetrical, or asymmetrical; elliptic, or linear; with both sutures parallelly curved; not inflated; compressed; with beak; straight; with solid beak the same color and texture as fruit; rounded at apex; aligned with longitudinal axis of fruit; rounded at base; aligned 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 not torulose; margin not constricted, or constricted; margin very slightly constricted along both margins; margin without sulcus; margin embellished; margin with wing(s); wing(s) present; wing(s) 2; wing(s) 5.5–11 mm wide; wing(s) sutural; wing(s) on both sutures; substipitate; with the stipe 2–3 mm long; indehiscent. Replum invisible. Epicarp dull; multicolored; mottled; tan; with brown overlay; mottling color combination variable; 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 uniformly veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with spongy layer over solid layer; coriaceous to chartaceous. Endocarp present; visible; dull; opaque; monochrome; greenish tan; scurfy and smooth; without adhering pieces of testa; septate; with septa thicker than paper, firm; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1–2; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 2 mm long; of 1 length only; filiform; straight. Aril present; fleshy; when fleshy marginal hilar; entire; covering less than 1/2 of seed; tan.

Seed: 16–20 mm long; 12–13 mm wide; 3–6 mm thick; not overgrown; not angular; asymmetrical; irregular; flattened; with surface smooth; with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes; with deep 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; mottled; with infrequent mottles; reddish brown; with brown overlay (darker); glabrous; not smooth; with elevated features and recessed features, or elevated features, or recessed features; wrinkled; pitted with small separate pits; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from hilum through lens and terminating before base of seed; not bifurcating; color of testa; slightly raised. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; ca. 1.5 mm long; with curved outline; circular to oval; apical according to radicle tip but marginal according to seed length; recessed; not within corona, halo, or rim. Lens discernible; with margins curved; circular; not in groove of raphe; confluent with hilum; recessed; same color as testa; brown; not within corona, halo, or rim. Endosperm absent. Cotyledons not smooth; dimpled once (below embryo); 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; notched at radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; yellow; inner face flat; glabrous on inner face. Embryonic axis oblique; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip curved; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Africa.

Old World; Africa.

Tribal Notes

Tribe Millettieae

Geesink (1981) treated this tribe, as others before him, under the tribal name Tephroseae, but we now know that its correct name is Millettieae. Recent tribal studies (Geesink, 1981, 1984; Polhill, 1994a, 1994b) have arranged the genera in alphabetical order without phylogenetic numbers. Geesink (1984) monographed tribe Millettieae, and presented descriptive notes about fruits and seeds and in situ fruit and seed drawings. However, we are not entirely following Geesink (1984) for generic parameters because he either questioned the status of many of his new genera or did not make the necessary species transfers. The few new genera which he clearly recognized are being accepted. Lavin et al. (1998) developed a preliminary infratribal classification of six informal groups using phytochrome nucleotides: Millettia group, Lonchocarpus group, Derris group, Tephrosia group, "primitive" group, and Phaseoleae group. Lavin (1987) transferred Sphinctospermum to Millettieae. Lavin and Doyle (1991) carried out cladistic analyses integrating morphological and chloroplast DNA data, and concluded that it is a member of Robineae where we have placed it (now 8.12).