Dipogon

Taxonomy

Dipogon F.M. Liebmann Ann. Sci. Nat. Bot. ser. 4. 2: 374. 1854.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.63.
Tribe: Phaseoleae.
Subtribe: Phaseolinae.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legume; unilocular; 3–4.5 cm long; 0.5–0.9 cm wide; 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; slightly falcate; with both sutures parallelly curved; not inflated; compressed; with beak; declined; with solid beak the same color and texture as fruit; short tapered at apex; oblique with longitudinal axis of fruit; tapered 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; substipitate; with the stipe 2–3 mm long; 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; multicolored; mottled; orange; with brown overlay; mottling color combination constant; with mottling over seed chambers; with surface texture uniform; glabrous; eglandular; without spines; smooth, or not smooth; not veined; not tuberculate; not exfoliating; without cracks, or with cracks; cracking oblique to fruit length; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without reniform canals; solid; chartaceous. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; septate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 3–5; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.5–1 mm long; of 1 length only; flattened; straight. Aril present; fleshy; when fleshy hippocrepiform rim-aril; entire; covering less than 1/2 of seed; 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: 4.1–7.1 mm long; 3.5–5 mm wide; 3–3.7 mm thick; not overgrown; angular; symmetrical; elliptic to ovate; terete; 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; mottled; with frequent 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; fully concealed; concealed by aril; without faboid split; larger than punctiform; 3–3.8 mm long; with straight outline; linear; marginal according to radicle tip; flush; within corona; corona color darker than testa. Lens barely discernible; 0.5–1 mm long; with margins straight; linear; not in groove of raphe; confluent with hilum; flush; similar color as testa; darker than testa; brown; within rim; rim color darker than testa. Endosperm apparently 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; without margins recessed; yellowish 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; linear; lobe tip curved; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule well developed; glabrous.

Distribution

South Africa, And cultivated elsewhere.

Old World; Africa (only South Africa).

Worldwide crop (cultivated in Europe, Australia, and the Indian Ocean in the Old World and the United States and South America in the New World).

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.