Pentaclethra

Taxonomy

Pentaclethra G. Bentham J. Bot. (Hooker) 2: 127. Apr 1840.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.1.01.
Tribe: Parkieae.
Species Studied - Species in Genus: 1 studied; 2 in genus.

Description

Fruit: A legume; unilocular; 30–74 cm long; 2–10 cm wide; 1–3 cm thick; 2–9 times longer than wide, or more than 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; broadly linear to oblong, or linear; not inflated; compressed; without beak; short tapered at apex; long tapered at base (up to 20 mm long); aligned with longitudinal axis of fruit; with the apex and base uniform in texture; ligneous; seed chambers externally visible, or invisible; margin not constricted; margin without sulcus; margin plain; wing(s) absent; stipitate; with the stipe 5–20 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures; apical and down; active; with valves revolute (elastically, forming 1–2 coils around large lumen), or twisting, or breaking (near or below middle, partially tearing away from one or both surfaces sutures often splitting during dehiscence). Replum invisible. Epicarp dull; monochrome; dark brown; with surface texture uniform; glabrous; eglandular; without spines; not smooth; with elevated features; not veined, or veined; irregularly veined; not tuberculate; exfoliating in part; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp present; surface not veined; 1-layered; without balsamic vesicles; with fibers; without reniform canals; fibrous throughout; ligneous. Endocarp present; visible; dull; opaque; monochrome; reddish brown; obliquely cracked; without adhering pieces of testa; subseptate; exfoliating in part; remaining fused to mesocarp and epicarp; entire. Seed(s) 3–8; length oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 2–4 mm long; of 1 length only; thick; triangular (3–5 mm wide at base). Aril absent.

Seed: 25–90 mm long; 20–55 mm wide; 5–15 mm thick; not overgrown; not angular; symmetrical; ovate to elliptic (with one margin curved and other subangulate); 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; glossy to dull; not modified by a bloom; colored; monochrome; brown; glabrous; not smooth; with elevated features; fanlike reticulate; osseous to coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines absent. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; fully concealed; concealed by funicular remnant; without faboid split; larger than punctiform; up to 5 mm long; with curved outline; elliptic; apical at apex of radicle tip; raised; within halo; halo darker than testa. Lens not discernible. Endosperm absent. Cotyledons smooth, or not smooth; fanlike veined; 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; completely concealing radicle; with lobes; with lobes touching (auriculate), or overlapping; without basal groin formed by lobes (when lobes only touching), or with basal groin formed by lobes (when lobes overlap); 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 moderately developed; glabrous.

Distribution

Central America, Northern South America, and tropical Africa.

New World and Old World; Mexico, Central America, and South America (northern); Peru, Brazil, Ecuador, and the Guianas; tropical Africa.

Generic Notes

Elias (1981) reported that Pentaclethra and Dimorphandra (1.1.43) are remarkably similar and possibly more closely related to each other than to other genera in their respective tribes. Fruit and seed characters support neither this conclusion nor the relationship of Pentaclethra to Parkia R. Brown. Based on their characters Pentaclethra is unique, belonging in its own primitive tribe, and Parkia should be placed in the more advanced tribe Mimoseae.