Platycyamus

Taxonomy

Platycyamus G. Bentham In C. F. P. Martius, Fl. Brasil. 15(1): 323. Jan 1862.

Subfamily: Faboideae.
Phylogenetic Number: 3.7.
Tribe: Millettieae.
Species Studied - Species in Genus: 1 studied; 2 in genus.

Description

Fruit: A legume; unilocular; 15–20 cm long; 3.5–4 cm wide; 0.4–0.5 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; falcate to fusiform; with both sutures parallelly curved; not inflated; flattened; without beak; tapered at apex; oblique with longitudinal axis of fruit; rounded at base to tapered at base; aligned with longitudinal axis of fruit, or oblique with longitudinal axis of fruit; with the apex and base uniform in texture; chartaceous; seed chambers externally invisible; margin not constricted; margin without sulcus; margin embellished; margin with ridge(s) and wing(s); wing(s) present; wing(s) 1; wing(s) 5–8 mm wide; wing(s) sutural; wing(s) on 1 suture; nonstipitate; indehiscent. Epicarp dull; monochrome; orange-brown or orangish brown; with surface texture uniform; pubescent and indurate; with hairs appressed; with 1 type of pubescence; puberulent; with pubescence golden; with pubescence uniformly distributed; with simple hairs; stiff; 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 present; thin; surface not veined; 2-layered; without balsamic vesicles; without fibers; without reniform canals; with vitriol layer over solid layer; chartaceous. Endocarp present; visible; dull; translucent; monochrome; yellow; smooth; without adhering pieces of testa; nonseptate; chartaceous; not exfoliating; remaining fused to mesocarp and epicarp; with wing(s) extending into epicarp; entire. Seed(s) 1–3; length parallel with fruit length; neither overlapping nor touching; in 1 series. Funiculus ca. 4 mm long; of 1 length only; flattened and thick; straight. Aril present; dry; when dry hippocrepiform rim-aril; entire; covering less than 1/2 of seed; brown.

Seed: 22–23 mm long; 13–14 mm wide; 2–4 mm thick; not overgrown; not angular; asymmetrical; reniform; flattened; with surface smooth; without visible radicle and cotyledon lobes; with deep hilar sinus; without umbo on seed faces; without medial ridge on each face. 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; not smooth; with recessed features; pitted with small separate pits; chartaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; partially concealed; concealed by aril; with faboid split; with the lips of the faboid split the same color as the rest of the hilum; larger than punctiform; ac. 3 mm long; with curved outline; elliptic to circular; apical according to radicle tip but marginal according to seed length; recessed; within rim; rim color of testa. Lens discernible; ca. 3 mm long; with margins straight; linear; not in groove of raphe; adjacent to hilum; ca. 1 mm from hilum; flush; same color as testa; brown; not within corona, halo, or rim. Endosperm absent. 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; partially concealing radicle; notched at 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 to perpendicular to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; bulbose; lobe tip slightly curved; oblique to cotyledons; centered between cotyledons; less than 1/2 length of cotyledons. Plumule moderately developed; glabrous.

Distribution

Brazil (1 sp.) and Peru (1 sp.).

New World; South America (Brazil and Peru); Peru, Brazil, and the Guianas.

Tribal Notes

Tribe Millettieae

Geesink (1981) treated this tribe, as others before him, under the tribal name Tephroseae, but we now know that its correct name is Millettieae. Recent tribal studies (Geesink, 1981, 1984; Polhill, 1994a, 1994b) have arranged the genera in alphabetical order without phylogenetic numbers. Geesink (1984) monographed tribe Millettieae, and presented descriptive notes about fruits and seeds and in situ fruit and seed drawings. However, we are not entirely following Geesink (1984) for generic parameters because he either questioned the status of many of his new genera or did not make the necessary species transfers. The few new genera which he clearly recognized are being accepted. Lavin et al. (1998) developed a preliminary infratribal classification of six informal groups using phytochrome nucleotides: Millettia group, Lonchocarpus group, Derris group, Tephrosia group, "primitive" group, and Phaseoleae group. Lavin (1987) transferred Sphinctospermum to Millettieae. Lavin and Doyle (1991) carried out cladistic analyses integrating morphological and chloroplast DNA data, and concluded that it is a member of Robineae where we have placed it (now 8.12).