Chrysoscias

Taxonomy

Chrysoscias E.H.F. Meyer Comment. Pl. Africae Austr. 139. 14 Feb-5 Jun 1836 ('1837').

Subfamily: Faboideae.
Phylogenetic Number: 3.10.78.
Tribe: Phaseoleae.
Subtribe: Cajaninae.
Species Studied - Species in Genus: 2 studied; 6 in genus.

Description

Fruit: A legume; unilocular; 1.7–2 cm long; 0.5–0.7 cm wide; 0.4–0.5 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with deciduous calyx, or persistent calyx; with calyx longer than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical; narrowly elliptic; not inflated; terete; with beak; straight (2–3 mm long); with solid beak the same color and texture as fruit; tapered at apex; aligned with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally invisible; margin constricted; margin without sulcus; margin plain; wing(s) absent; 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; with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; velutinous; with pubescence white or yellowish white; with pubescence uniformly distributed; with simple hairs (antrorse); pliable; with hair bases swollen (yellow); eglandular; without spines; not smooth; with recessed features; not veined; not tuberculate; obliquely, shallowly grooved; 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; chartaceous. Endocarp present; visible; glossy; opaque; monochrome; white; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 1, or 2; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 0.5 mm long; flattened; broadly triangular. Aril present; fleshy; when fleshy 2-lipped rim-aril; entire; covering less than 1/2 of seed; without tongue (or flap) on lips of 2-lipped rim-aril.

Seed: 3.6–4.7 mm long; 3–3.7 mm wide; 2.7–3 mm thick; not overgrown; not angular; symmetrical; ovate; 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 to glossy; not modified by a bloom; colored; mottled, or monochrome; with frequent mottles; black, or brown (dark); with brown overlay; glabrous; smooth; coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. 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; larger than punctiform; 1.5–2.8 mm long; with curved outline; elliptic; marginal according to radicle tip; recessed; within halo, or not within corona, halo, or rim; halo lighter than testa. Lens discernible; 0.5–0.8 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; recessed, or flush; same color as testa; black, or brown; within halo; halo color lighter than testa. Endosperm absent. Cotyledons smooth; with 2 outer faces on each cotyledon, one flat and the other 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; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; dark brown; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; with a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip straight; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

South Africa.

Old World; Africa (South Africa).

Generic Notes

The status of Chrysoscias is ambiguous. It has been maintained as a genus (Lackey 1981; Polhill 1994b), and synonymized under Rhynchosia (10.80) (Grear 1978; Arnold and De Wet 1993). Pending detailed studies, we have accepted it as a genus.

Tribal Notes

Tribe Phaseoleae

Bruneau et al. (1995) carried out cladistic analyses of tribe Phaseoleae using chloroplast DNA restriction site data. Their results indicated that the tribe is not monophyletic and that the tribal delimitations between Phaseoleae and Desmodieae (11) and between Phaseoleae and Millettieae (7) are problematic.