Mecopus

Taxonomy

Mecopus J.J. Bennett In J. J. Bennett et R. Brown, Pl. Jav. Rar. 154. Mai 1840.

Subfamily: Faboideae.
Phylogenetic Number: 3.11.15.
Tribe: Desmodieae.
Subtribe: Desmodiinae.
Species Studied - Species in Genus: 1 studied; 1 in genus.

Description

Fruit: A legume; unilocular; 0.27 cm long; 0.2 cm wide; 0.1 cm thick; length less than twice as long as width; with persistent androecial sheath, or deciduous androecial sheath; with deciduous corolla; with deciduous calyx, or persistent calyx; with calyx shorter than fruit; without orifice formed by curving of fruit or fruit segments; straight; not plicate; not twisted; asymmetrical; with 1 straight and 1 curved suture; widest near middle or D-shaped; not inflated; compressed; without beak; short tapered at apex; oblique with longitudinal axis of fruit; short tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally visible; seed chambers with the raised seed chambers not torulose; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 50–60 mm long (and reflexed into "bird cage" where fruits are "caught"); with all layers dehiscing; splitting along suture(s). Dehiscence of valves along 1 suture; apical and down; passive. Replum invisible. Epicarp dull; monochrome; reddish brown, or tan (reddish); with surface texture uniform; pubescent and indurate; with hairs erect; with 1 type of pubescence; puberulent; with pubescence gray; with pubescence uniformly distributed; with simple hairs; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined; not tuberculate; not exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; monochrome; reddish brown, or tan (reddish); smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 1, or 2; length parallel with fruit length; neither overlapping nor touching (if 1-seeded); in 1 series. Funiculus of 1 length only; straight. Aril present; dry; when dry rim-aril; entire; reddish brown.

Seed: 1.7–2 mm long; 1.1–1.2 mm wide; 0.6–0.7 mm thick; not overgrown; not angular; asymmetrical; reniform (sub); compressed; 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; reddish brown, or tan; glabrous; smooth; 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; flush; within halo; halo of testa. Lens discernible; with margins straight, or curved; oblong; oblong; not in groove of raphe; confluent with hilum; mounded; dissimilar color from testa; darker than testa; darker reddish brown; not within corona, halo, or rim. Endosperm present; thick; 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; white; 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

India to southern China and Malay Islands.

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

Generic Notes

The seeds dehisce from the 1-Seeded fruits while on the plants. Apparently, the "bird-cage" heads fall intact, and the seeds are shed as the heads are transported on animal fur.

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).