Desmodium

Taxonomy

Desmodium A.N. Desvaux Nom. cons. J. Bot. Agric. 1: 122. Mar 1813.

Subfamily: Faboideae.
Phylogenetic Number: 3.11.09.
Tribe: Desmodieae.
Subtribe: Desmodiinae.
Species Studied - Species in Genus: 69 studied; ca. 300 in genus.

Description

Fruit: A loment (or a loment segment), or a legume; unilocular; 0.8–5 cm long; 0.08–2.5 cm wide; 0.02–0.09 cm thick; 2–9 times longer than wide; with deciduous androecial sheath, or persistent androecial sheath; with deciduous corolla; with persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight, or curved (or slightly curved), or contorted; not plicate, or plicate (D. styracifolium (P. Osbeck) E.D. Merrill plicate when young and becoming straight with age); not twisted, or twisted; symmetrical, or asymmetrical; linear, or circular (with notch at funiculus), or dolabriform, or irregular, or samaroid; with 1 straight and 1 curved suture, or both sutures parallelly curved, or both sutures unequally curved; narrowing in several places, resembling Desmodium (3.11.09) fruit; not inflated, or inflated; flattened, or compressed; without beak, or with beak; with solid beak the same color and texture as fruit; rounded at apex, or short tapered at apex; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; short tapered at base, or tapered at base, or long tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; membranous, or coriaceous, or chartaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin constricted, or not constricted; margin constricted on 1 margin and slightly constricted on the other margin, or slightly constricted only on 1 margin, or constricted only on 1 margin, or slightly constricted along both margins; margin without sulcus; margin plain, or embellished; margin with prickles (at least stiff usually hooked hairs), or wing(s); wing(s) present; wing(s) 1; wing(s) 0.1–10 mm wide; wing(s) samaroid; wing(s) on 1 suture; substipitate, or stipitate; with the stipe 1–20 mm long; indehiscent, or with all layers dehiscing (tardily); splitting along suture(s). Dehiscence of valves along 1 suture; medial and up and down; passive. Replum invisible (most spp.), or visible (at least 1 sp. in Panama (Schubert, 1980)). Loment indehiscent (most spp.), or dehiscing along 1 suture (few spp., especially spp. in subtribe Sagotia); segments (articles) inconspicuous; segments (articles) 2–30 mm long; segments (articles) widest across seed area; segments (articles) with all essentially similar in shape; segments (articles) D-shaped, or triangular, or curved, or quadrangular, or circular (with notch at funiculus more or less dolobriform). Epicarp dull; monochrome, or multicolored; mottled; brown (various shades and combinations, especially reddish), or tan (to greenish); with brown overlay (reddish), or purple overlay; with surface texture uniform; glabrate, or glabrous; with hairs erect, or appressed; with 1 type of pubescence, or 2 types of pubescence; pilose, or puberulent, or velutinous; with pubescence golden, or brown, or yellow, or gray-brown; with golden hooked hairs and gray plain hairs; with pubescence uniformly distributed; with simple hairs (plain and hooked hairs mixed, plain hairs, or hooked hairs, and straight, retrorse, or antrorse); pliable, or stiff; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; wrinkled; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present, or absent; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; chartaceous, or coriaceous. Endocarp present; visible; glossy, or dull; opaque; monochrome; tan; spongy, or hairy (rarely, in a single species, D. auricomum R. Graham); without adhering pieces of testa; with hairs in longitudinal rows (D. auricomum R. Graham); septate; with septa thicker than paper, firm; with septa eglandular; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; remaining fused to epicarp; with wing(s) extending into epicarp; entire. Seed(s) 1–12; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus 0.1–4 mm long (usually less than 0.4); of 1 length only; thick, or flattened, or filiform; straight, or curved, or S-curved. Aril present, or absent; dry; when dry rim-aril, or cupshaped (only D. microphyllum (C.P. Thunberg) A.P. de Candolle); entire; covering less than 1/2 of seed.

Seed: 0.7–12.5 mm long; 0.5–5 mm wide; 0.5–1 mm thick; not overgrown; not angular; asymmetrical; D-shaped, or oblong, or quadrangular, or rectangular, or reniform, or linear; flattened, or compressed; with surface grooved (D. oojeinensis (W. Roxburgh) H. $$Ohasi), or smooth; longitudinal and oblique; 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, or glossy; not modified by a bloom; colored; monochrome, or mottled and streaked; with frequent mottles; with frequent streaks; dark to light reddish brown to brown, or tan, or green, or olive (green); with brown overlay (dark reddish); glabrous; smooth, or not smooth; with elevated features, or recessed features; faintly wrinkled; pitted with small separate pits; chartaceous, or coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or fully 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; punctiform, or larger than punctiform; 0.1–1 mm long; with curved outline, or straight outline; circular; oblong, or linear; marginal according to radicle tip, or between cotyledon and radicle lobe; recessed; within rim, or not within corona, halo, or rim; rim color darker than testa. Lens discernible; 0.1–0.5 mm long; with margins straight, or curved; oblong; circular, or oblong, or elliptic, or 2 circular mounds separated by groove; not in groove of raphe; confluent with hilum; flush; dissimilar color from testa; darker than testa; reddish brown, or black, or yellow (reddish); 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, or embryo. Cotyledons smooth, or not 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; not concealing radicle; entire over radicle; without lobes; with the interface division terminating at base of radicle; without margins recessed; yellow, or tan, or green; 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; linear; deflexed and parallel to cotyledon length; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed, or well developed, or rudimentary; glabrous.

Distribution

Worldwide.

New World, or Old World; pan warm temperate to pansubtropical to pantropical; Canada to United States to West Indies to Mexico to Central America to South America (United States (not west of Rocky Mountains)); Argentina, Peru, Brazil, Ecuador, and the Guianas; Russia to China to Japan to Africa to Madagascar to Southwest Asia to Indian Ocean to India to Indochina to Indonesia and the Philippines to New Guinea to Australia to Pacific to Fiji to Korea to Macaronesia.

Generic Notes

Several regional or country treatments were reviewed: Schubert (1980), Panama; Oliveira (1983, 1990), Brazil; Verdcourt (1974), Zambia; Schubert (1952, 1954), Congo; Ohashi (1973), Asia; and Ohashi (1988), Hawaii. Verdcourt (1977) synonymized Papilionopsis C.G.G.J.van Steenis with Desmodium, and Ohashi (1982b) transferred Murtonia W.G. Craib to Desmodium as a subgenus. Although most species of Desmodium have indehiscent lomentaceous fruits, a few species have dehiscent loments, especially in subgenus Sagatia (O.P. Swartz) A.P. de Candolle, D. heterophyllum (C.L. von Willdenow) A.P. de Candolle, and D. microphyllum (C.P. Thunberg) A.P. de Candolle. Desmodium auricomum loments have a longitudinal band of dense hairs on the lateral surfaces. All species of Desmodium except one, D. microphyllum, have small, dry rim-arils (Ohashi, 1973); D. microphyllum has small, dry cupshaped arils (Ohashi, 1973).

Tribal Notes

Tribe Desmodieae

Ohashi et al. (1981) started their treatment of the Desmodieae with these thoughts: "A sensible classification of Desmodieae is prejudiced by the traditional over-weighting of fruit characters." (sic) "The fruit normally consists of indehiscent jointed articles, but fruits that open have arisen at least seven times..." They supplemented their text with a fruit-seed plate. They placed Brya and Cranocarpus (11.02), the only two New World endemic genera, in the new subtribe Bryinae, "characterized most notably by glochidiate hairs." Bailey et al. (1997), using the chloroplast rpl2 intron and ORF184, suggested that Brya, Cranocarpus, Phylacium (11.22), and Neocollettia (11.26) are not members of Desmodieae and that they probably belong in Aeschynomeneae (14).