Pterolobium

Taxonomy

Pterolobium R. Brown ex R. Wight & G.A.W. Arnott Nom. cons. Prodr. 283. Oct (prim.) 1834.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.1.25.
Tribe: Caesalpinieae.
Group: Caesalpinia.
Species Studied - Species in Genus: 8 studied; 11 in genus.

Description

Fruit: A legumelegume:
usually dry, dehiscent fruit derived from a single carpel that opens along two longitudinal sutures
; unilocular; 3–6.5 cm long; 0.8–2 cm wide; 0.2–1 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; curved, or straight; not plicate; not twisted; symmetrical, or asymmetrical; with 1 straight and 1 curved suture; narrowing in several places, resembling Desmodium (3.11.09) fruit; not inflated; flattened; without beak; tapered at apex; aligned with longitudinal axis of fruit; tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous and ligneous (wing & seed chamber); seed chambers externally visible; margin constricted, or not constricted; margin constricted only on 1 margin; margin without sulcus; margin embellished; margin with wing(s); wing(s) present; wing(s) samaroid; wing(s) apical; substipitate to nonstipitate; indehiscent. Replum invisible. Epicarp dull; multicolored, or monochrome; mottled; red, or purple to brown (or seed chamber darker than wing); with surface texture uniform; glabrous to pubescent and indurate; with hairs erect; eglandular; without spines; smooth, or not smooth; with elevated features; veined, or not veined; reticulately veined; not tuberculate; rugose; not 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; ligneous. Endocarp present; visible; dull to glossy; opaque; monochrome; dull brown, or black; without adhering pieces of testa; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 1; length parallel with fruit length. Funiculus 0.1–1 mm long; of 1 length only; filiform; straight, or triangular. Aril absent.

Seed: 8–11 mm long; 5–7 mm wide; 2–3 mm thick; not overgrown; not angular; symmetrical, or asymmetrical; elliptic to ovate; 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; not modified by a bloom; colored; monochrome; brown, or green; glabrous; not smooth; with elevated features; rugose (faint); coriaceous. Pleurogram absent. Pseudopleurogram absent. Fracture lines present; concentric. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible, or fully concealed; concealed by funicular remnant; without faboid split; punctiform; apical at apex of radicle tip; flush; not within corona, halo, or rim. Lens discernible; 0.1–0.5 mm long; with margins curved; elliptic to circular; not in groove of raphe; mounded, or flush; dissimilar color from testa; black to 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 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; 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; centered between cotyledons. Plumule well developed; glabrous.

Distribution

Southern and eastern Africa to southeastern Asia.

Old World; Southern and eastern Africa to China to Southwest Asia to India to Indochina to Indonesia and the Philippines (southeastern Asia).

Generic Notes

Fruits of Pterolobium appear identical to the fruits of Pterogyne (1.37), except for the location of the style (or stylar remnant). In Pterolobium the style is at the apex of the wing (not the seed chamber), whereas in Pterogyne the style is at the apex of the seed chamber (not the wing). The seed chamber is apical and the wing dorsal in the similar samaroid fruits of Neoapaloxylon (4.29) and Brandzeia (4.28), both in the Detarieae. Vidal and Thol (1974) and Thol and Hideaux (1977) monographed the genus.