Plathymenia

Taxonomy

Plathymenia G. Bentham Nom. cons. J. Bot. (Hooker) 2: 134. Apr 1840.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.15.
Tribe: Mimoseae.
Group: Plathymenia.
Species Studied - Species in Genus: 2 studied; 4 in genus.

Description

Fruit: A legume; unilocular; 7–17 cm long; 1.5–5 cm wide; 0.2–0.3 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; symmetrical; oblong to linear; not inflated; flattened; without beak; rounded at apex; aligned with longitudinal axis of fruit; short tapered at base to long tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous to ligneous; seed chambers externally invisible, or visible; margin slightly constricted to constricted (especially near apex or base); margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 10–20 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down (reaching the base); passive. Replum invisible. Epicarp dull; monochrome; brown to black; with surface texture uniform; glabrous; eglandular; without spines; smooth to not smooth; with elevated features; not veined, or veined (faintly); not tuberculate; checking and exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; without fibers; without reniform canals; solid; coriaceous to ligneous. Endocarp present; visible; dull; opaque; mottled; tan; with mottling above and below seed chambers; with dark tan overlay; smooth; without adhering pieces of testa; septate; not exfoliating; separating from mesocarp; separating into 1-seeded winged segments. Seed(s) 8–19; length transverse to fruit length; neither overlapping nor touching; in 1 series. Funiculus up to 25 mm long; of 1 length only; filiform; contorted. Aril absent.

Seed: 7–11 mm long; 4–6 mm wide; 1–2 mm thick; not overgrown; not angular; symmetrical; ovate to oblong; compressed; with surface smooth; without visible radicle and cotyledon lobes; without hilar sinus; faintly 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 to glossy; not modified by a bloom; colored; monochrome; medium brown; glabrous; smooth (but with line to groove arising near micropyle crossing pleurogram terminating at faint umbo); coriaceous. Pleurogram present; 100 %. Pseudopleurogram absent. Fracture lines present. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; without faboid split; punctiform; apical at apex of radicle tip; recessed; not within corona, halo, or rim. Lens either discernible (or barely discernible as mound of dark-brown tissue); if discernible 0.4 mm long; with margins straight; oblong; not in groove of raphe; mounded; similar color as testa; lighter than testa; tan (surrounded by darker brown); not within corona, halo, or rim. Endosperm present; thin; not pluglike and not resembling tip of radicle; adnate to testa. Cotyledons smooth; both outer faces flat; 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 (or 75% of radicle exposed); split over radicle; with lobes; with lobes touching (auriculate); without basal groin formed by lobes; with the interface division terminating at base of radicle; without margins recessed; inner face flat; glabrous on inner face. Embryonic axis straight; parallel to length of seed; without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; straight with embryonic axis; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Tropical South America.

New World; tropical South America; Argentina, Brazil, and Ecuador.

Generic Notes

Plathymenia spp. "dehisce" 1-seeded, winged, indehiscent endocarp segments similar to Wallaceodendron (2.5.16).