Spatholobus

Taxonomy

Spatholobus J.C. Hasskarl Flora 25(2) (Beibl.): 52. 28 Sep 1842.

Subfamily: Faboideae.
Phylogenetic Number: 3.10.05.
Tribe: Phaseoleae.
Subtribe: Erythrininae.
Species Studied - Species in Genus: 9 studied; 15 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 4–15 cm long; 1.3–4.5 cm wide; 0.4–0.7 cm thick; 2–9 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; asymmetrical; samaroid; with both sutures unequally curved; not inflated; flattened; without beak; rounded at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; rounded at base; oblique with longitudinal axis of fruit; with the apex and base uniform in texture; leathery and chartaceous; seed chambers externally visible; margin not constricted; margin without sulcus; margin embellished; margin with thickened sutural areas (especially dorsally), or wing(s); wing(s) present; wing(s) 1; wing(s) 13–45 mm wide (and 80–105 mm long); wing(s) samaroid; wing(s) basal; substipitate, or stipitate; with the stipe 0.1–6 mm long; indehiscent. Epicarp dull; monochrome; brown, or tan; with surface texture uniform; glabrous to pubescent but soon deciduous; with hairs erect; with 1 type of pubescence; pilose; with pubescence golden to brown; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined; transversely veined relative to fruit length, or reticulately veined, or irregularly veined; not tuberculate; sometimes dotted; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present (on seed chamber); thin; surface not veined; 1-layered, or 2-layered; without balsamic vesicles; with fibers, or without fibers; without reniform canals; solid; with fibers embedded in mealy tissue over solid layer; with vitriol layer over solid layer; coriaceous, or chartaceous. Endocarp present; visible; dull; opaque; monochrome, or mottled; brown, or tan; with mottling over seed chambers; with brown overlay (darker near margins of seed chamber); fibrous; without adhering pieces of testa; nonseptate; coriaceous; not exfoliating; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp; entire. Seed(s) 1; length parallel with fruit length. Funiculus 1 mm long; flattened; triangular. Aril absent.

Seed: 18.6–32 mm long; 11–23 mm wide; 4–6.7 mm thick; not overgrown; not angular; asymmetrical; variously irregular; 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; dull; not modified by a bloom; colored; monochrome; dark brown; glabrous; smooth, or not smooth; with elevated features; wrinkled; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe visible; from hilum to near base of seed and terminating; not bifurcating; color of testa, or darker than testa; black; raised. Hilum present; visible, or partially concealed; concealed by funicular remnant; with faboid split, or without faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; 2.5–4.6 mm long; with curved outline; elliptic; marginal according to radicle tip; recessed; within rim; rim color of testa. Lens not discernible. Endosperm absent. Cotyledons not smooth; wrinkled; both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin not entire 180 degrees from base of radicle; notched; similar at apex; partially concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; tan; inner face flat; glabrous on inner face. Embryonic axis oblique; oblique to length of seed; with a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; linear; lobe tip straight; deflexed and parallel to cotyledon width, or oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed; glabrous.

Distribution

Tropical Asia.

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

Generic Notes

Ridder-Numan and Wiriadinata (1985) monographed Spatholobus, and Ridder-Numan (1992) added a new species and made some other revisions. Using cladistic methodology, Ridder-Numan (1996) presented an extensive analysis of its biogeography. Ridder-Numan (1995) and Ridder-Numan and Van Der Ham (1997) proposed that this genus was closely related to Butea (10.04) and Meizotropis (10.06) and to Kunstleria in Millettieae. They considered Spatholobus to be intermediate in its characteristics between Phaseoleae and Millettieae, and suggested that its position was either basal in Phaseoleae or in the trasition zone between the two tribes.

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.