Dysolobium

Taxonomy

Dysolobium (G. Bentham) D. Prain J. Asiat. Soc. Bengal, Pt. 2, Nat. Hist. 66(2): 425. 1897.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.50.
Tribe: Phaseoleae.
Subtribe: Phaseolinae.
Species Studied - Species in Genus: 2 studied; 4 in genus.

Description

Fruit: A legume; unilocular; 3.5–20 cm long; 0.8–2.3 cm wide; 2–9 times longer than wide, or more than 9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; symmetrical; linear; not inflated; compressed to terete; without beak; tapered at apex, or short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base, or rounded at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous to ligneous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin plain, or embellished; margin with ridge(s), or 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; with surface texture uniform; pubescent and indurate; with hairs erect, or appressed; with 1 type of pubescence; puberulent, or velutinous; with pubescence golden; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; not veined; not tuberculate; rugose and wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thick; surface not veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with solid layer over solid layer; ligneous to coriaceous. Endocarp present; visible; dull; opaque; monochrome; brown to tan; 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) 3–15; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 1–3 mm long; of 1 length only; flattened; straight, or triangular. Aril present; dry; when dry rim-aril and tongue-aril; entire; cream to tan.

Seed: 4.8–13.7 mm long; 4.7–10 mm wide; 4.1–11 mm thick; not overgrown; not angular; symmetrical; circular to oblong; 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; monochrome; dark brown; glabrous; smooth, or not smooth; with elevated features; reticulate; 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; 1.7–6.1 mm long; with curved outline; elliptic, or oval; apical according to radicle tip but marginal according to seed length; recessed; within rim, or not within corona, halo, or rim; rim color of testa. Lens discernible; 1.3–1.7 mm long; with margins straight, or curved; linear; circular; not in groove of raphe; confluent with hilum; recessed; same color as testa; dark brown; within rim, or not within corona, halo, or rim; rim color of 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; orange; 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 well developed; glabrous.

Distribution

Asia.

Old World; India, Indochina, China, and Indonesia and the Philippines.

Generic Notes

Lackey (1981) noted "the genus resembles Psophocarpus" (10.51) "in many respects, but Maréchal et al. (1978) doubted a close natural relationship of the two genera." Our seed and fruit data do not support Lackey's conclusion, but rather that of Maréchal. Welzen and Hengst (1985) monographed Dysolobium. Only one fruit was studied; additional information was taken from Welzen and Hengst.

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.