Stylosanthes

Taxonomy

Stylosanthes O.P. Swartz Prodr. 7, 108. 20 Jun-29 Jul 1788.

Subfamily: Faboideae.
Phylogenetic Number: 3.14.25.
Tribe: Aeschynomeneae.
Subtribe: Stylosanthinae.
Species Studied - Species in Genus: 25 studied; ca. 25 in genus.

Description

Fruit: A lomentloment:
usually dry fruit derived from a single carpel that breaks transversely into one-seeded fruit segments
(or a lomentloment:
usually dry fruit derived from a single carpel that breaks transversely into one-seeded fruit segments
segment); 0.4–0.9 cm long; 0.08–0.25 cm wide; 0.01–0.02 cm thick; 2–9 times longer than wide; with deciduous androecial sheath; with deciduous corolla; with persistent calyx, or deciduous calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical; rectangular (with or without apical beak); with 1 straight and 1 curved suture, or both sutures parallelly curved; widest near middle or D-shaped; not inflated; compressed; with beak; straight, or declined, or coiled; with solid beak the same color and texture as fruit; long tapered at apex to tapered at apex to short tapered at apex; aligned with longitudinal axis of fruit; short tapered at base, or truncate at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous to coriaceous, or fragile, thinner than chartaceous, like Trifolium; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin constricted, or not constricted; margin constricted along both margins, or constricted on 1 margin and slightly constricted on the other margin; margin without sulcus; margin plain; wing(s) absent; nonstipitate; indehiscent. Replum invisible. Lomentloment:
usually dry fruit derived from a single carpel that breaks transversely into one-seeded fruit segments
indehiscent; segments (articles) inconspicuous; segments (articles) 2–4.5 mm long; segments (articles) widest across seed area; segments (articles) with apical 1 different shape than middle one(s), or basal 1 different shape than middle one(s), or apical 1 different shape than basal 1; segments (articles) D-shaped. Epicarp dull; monochrome; with surface texture uniform, or not uniform, with patches of different texture not restricted to the base and apex; glabrous, or pubescent and indurate, or pubescent but soon deciduous; with hairs erect; with 1 type of pubescence; pilose, or puberulent, or villous; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined; longitudinally veined relative to fruit length, or reticulately veined (with 2 prominent longitudinal veins); not tuberculate, or tuberculate (minutely in S. guianensis); tuberculate (minutely in S. guianensis); not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; tan; smooth; without adhering pieces of testa; septate; with septa thicker than paper, firm; with septa eglandular; coriaceous to chartaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 1, or 2; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus of 1 length only; thick; straight. Aril absent.

Seed: 1.9–3 mm long; 1.4–2.5 mm wide; 0.6–1.2 mm thick; not overgrown; not angular; asymmetrical; ovate, or reniform (with prominent radicle lobe (beaklike)); compressed; with visible radicle and cotyledon lobes; without external groove between 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; not modified by a bloom; colored; monochrome; black, or brown (to reddish-brown), or tan; smooth; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; punctiform; between cotyledon and radicle lobe; flush; not within corona, halo, or rim. Lens discernible; with margins curved; circular; not in groove of raphe; adjacent to hilum; 0.5 mm from hilum; mounded; dissimilar color from testa; darker than testa; black; not within corona, halo, or rim. Endosperm present, or absent; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to testa. Cotyledons smooth; 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; similar at apex; partially concealing radicle; split over radicle; with lobes; with lobes not touching; with the interface division terminating at base of radicle; without margins recessed; yellow; inner face flat; glabrous on inner face. Embryonic axis deflexed; oblique to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip curved; deflexed and parallel to cotyledon width; centered between cotyledons; less than 1/2 length of cotyledons. Plumule rudimentary; glabrous.

Distribution

United States, West Indies, Mexico, Central America, South America (to northern Argentina and Galapagos Islands), central and southern Africa, Madagascar, southern India, Sri Lanka, and adventive in Indonesia to Australia.

New World, or Old World; pantropical to pansubtropical to pan warm temperate; United States to West Indies to Mexico to Central America to South America (and Galapagos Islands); Argentina, Peru, Brazil, Ecuador, and the Guianas; central and southern Africa, Madagascar, Southwest Asia, Indonesia and the Philippines, and Macaronesia (Asia (southern India and Sri Lanka) and Indonesia (adventive) and Australia (adventive)).

Worldwide crop.

Generic Notes

Mohlenbrock (1957) revised Stylosanthes and amended his revision (Mohlenbrock, 1963). Kirkbride and Kirkbride (1987) established the correct names for the two sections in the genus, and our studied species were obtained nearly equally from both sections. Mohlenbrock (1963) provided a key and fruit illustrations of the 30 species which he recognized. Mohlenbrock (1957) noted that the lower (of two) articles is usually densely pilose to glabrescent and aborted to fertile while the upper article is glabrous or puberulent to sericeous to minutely tuberculate. The relative beak-upper article lengths are diagnostic. t'Mannetje (1984) reported on the species of this genus and has excellent fruit drawings. Both Sousa Costa and Ferreira (1984) and Burkart (1952) have excellent fruit and seed drawings. Reis and Martins (1989a, 1989b) present interesting data on seed germination of apical and basal section seeds and on the distributional potential of the upper one-half of the legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
versus the lower one-half of the legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
. Some species of Stylosanthes have agronomic potential, especially in Australia and South America (Stace and Edye, 1984).

Tribal Notes

Tribe Aeschynomeneae

Rudd (1981a) recognized four subtribes of Aeschynomeneae: Ormocarpinae V.E. Rudd (genera 3.14.01–3.14.08), Aeschynomeninae (genera 3.14.09–3.14.16), Discolobinae (A.E. Burkart) V.E. Rudd (genus 3.14.17: Discolobium), Poiretiinae (A.E. Burkart) V.E. Rudd (genera 3.14.18–3.14.21), and Stylosanthinae (G. Bentham) V.E. Rudd (genera 3.14.22–13.4.26). Tribal and subtribal placement of Diphysa is based on Lavin (1987; Polhill, 1994a, 1994b), and not on Polhill and Sousa (1981), who placed Diphysa in Robinieae. Bailey et al. (1997), using the chloroplast rpl2 intron and ORF184, suggested that Brya (11.01), Cranocarpus (11.02), Phylacium (11.22), and Neocollettia (11.26) are not members of Desmodieae (11) and that they probably belong in Aeschynomeneae.