Pseudarthria

Taxonomy

Pseudarthria R. Wight & G.A.W. Arnott Prodr. 209. Oct (prim.) 1834.

Subfamily: Faboideae.
Phylogenetic Number: 3.11.11.
Tribe: Desmodieae.
Subtribe: Desmodiinae.
Species Studied - Species in Genus: 3 studied; 4–6 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 1.3–2 cm long; 0.3–0.5 cm wide; 0.1–0.13 cm thick; 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; straight, or curved (slightly); not plicate; not twisted; asymmetrical; oblong; with both sutures nearly straight; not inflated; flattened; with beak, or without beak; straight; with solid beak the same color and texture as fruit; rounded at apex; aligned with longitudinal axis of fruit; short tapered at base; oblique with longitudinal axis of fruit, or aligned with longitudinal axis of fruit; with the apex and base uniform in texture; membranous; seed chambers externally invisible, or visible (faintly); seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain; wing(s) absent; substipitate; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along 1 suture; apical and down (assumed); active; with valves reflexing. Replum invisible. Epicarp dull; monochrome; dark reddish brown; with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence golden (P. viscida (C. Linnaeus) R. Wight & G.A.W. Arnott with hooked-tipped hairs), or gray (P. hookeri without hooked-tipped hairs or P. fagifolia J.G. Baker with straight- and hooked-tipped hairs); with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; not veined, or veined; transversely veined relative to fruit length and reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; thin; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous (sub). Endocarp present; visible; dull; opaque; monochrome; reddish brown; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; without wings; entire. Seed(s) 5–8; length transverse to fruit length, or oblique to fruit length; touching; in 1 series. Funiculus 10 mm long; of 1 length only; filiform; S-curved, or curved. Aril present; dry; when dry rim-aril; entire; reddish brown.

Seed: 2.5 mm long; 1.5 mm wide; 1 mm thick; not overgrown; not angular, or angular; asymmetrical; reniform, or oblong, or triangular, or irregular; compressed; with surface smooth; without visible radicle and cotyledon lobes, or with visible radicle and cotyledon lobes; without external groove between radicle and cotyledon lobes, or with external groove between radicle and cotyledon lobes (faintly); with external groove between radicle and cotyledon lobes same color as testa; without hilar sinus; with 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; reddish brown, or tan (to greenish or reddish), or black (P. viscida), or orange (seeds have been described as orange); glabrous; smooth (P. hookeri and P. fagifolia), or not smooth (P. viscida); with elevated features; shagreen; coriaceous. 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; marginal according to radicle tip, or between cotyledon and radicle lobe; barely recessed; not within corona, halo, or rim, or within halo (faintly); halo of testa. Lens not discernible, or discernible (faintly); with margins straight, or curved; somewhat linear, or triangular; not in groove of raphe; confluent with hilum; flush; similar color as testa, or dissimilar color from testa; darker than testa; reddish brown, or tan (greenish); not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; covering entire embryo; adnate to embryo. 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; not 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 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; glabrous.

Distribution

Old World tropics.

Old World; Africa to Madagascar to Indian Ocean to India to Indochina to Indonesia and the Philippines to New Guinea to Pacific.

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).