Spathionema

Taxonomy

Spathionema P.H.W. Taubert In Engler, Pflanzenwelt Ost.-Afrikas C: 224. 1895.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.55.
Tribe: Phaseoleae.
Subtribe: Phaseolinae.
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; 2.5–3.5 cm long; 0.9–1 cm wide; 0.4 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; slightly curved; not plicate; not twisted; asymmetrical; falcate; with both sutures parallelly curved; not inflated; flattened to compressed; without beak, or with beak; declined; with solid beak the same color and texture as fruit; rounded at apex; oblique with longitudinal axis of fruit; rounded at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin embellished; margin with thickened sutural areas; 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, or multicolored; mottled; brown to tan; with brown overlay; mottling color combination variable; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with solid layer over solid layer; coriaceous. Endocarp present; visible; dull to glossy; opaque; monochrome, or mottled; tan to white; with mottling over seed chambers; with tan overlay; fibrous to smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 2; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 1–1.2 mm long; of 1 length only; flattened; triangular. Aril present; dry; when dry 2-lipped rim-aril; entire; with tongues (or flap) on lips of 2-lipped rim-aril; with 1 tongue or flap on 1 lip of 2-lipped rim-aril; cream.

Seed: 8.5–10.7 mm long; 6.5–9.5 mm wide; 1.5–3.5 mm thick; not overgrown; not angular; symmetrical to asymmetrical; ovate; 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; glossy to dull; not modified by a bloom; colored; mottled; with frequent mottles, or infrequent mottles; brown; with brown overlay (darker); glabrous; smooth; chartaceous. 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; 1.8–3 mm long; with curved outline; elliptic; apical according to radicle tip but marginal according to seed length; flush; within rim; rim color of testa, or darker than testa. Lens discernible; 1–1.8 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; recessed; same color as testa; brown; within rim; rim color of testa. 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; notched at radicle; without lobes; with the interface division terminating at base of radicle; with margin(s) recessed (slightly); with 1 margin recessed; recessed on same side as radicle; white; 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; triangular; lobe tip straight; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

Tropical eastern Africa.

Old World; Africa.

Generic Notes

Verdcourt (1971) gave a more exact distribution for this 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.