Macrolobium

Taxonomy

Macrolobium J.C.D. von Schreber Nom. cons. Gen. 30. Apr 1789.

Subfamily: Caesalpinioideae.
Phylogenetic Number: 1.4.72.
Tribe: Detarieae.
Group: Macrolobium.
Species Studied - Species in Genus: 24 studied; 60 in genus.

Description

Fruit: A legume; unilocular; 2.8–23 cm long; 1.5–6.5 cm wide; 0.4–3 cm thick; length less than twice as long as width to 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 to curved; not plicate; not twisted; symmetrical, or asymmetrical; nearly circular to oblong; with 1 straight and 1 curved suture; widest near middle or D-shaped, or widest near apex (oblong); not inflated; flattened to compressed; without beak; tapered at apex; aligned with longitudinal axis of fruit to oblique with longitudinal axis of fruit; rounded at base; aligned with longitudinal axis of fruit to right angled 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, or embellished; margin with thickened sutural areas, or flange(s) (ventrally); wing(s) absent; stipitate to substipitate (swollen in M. angustifolium); with the stipe 6–20 mm long; with all layers dehiscing, or indehiscent; splitting along suture(s). Dehiscence of valves along both sutures; active; with valves breaking, or enrolling. Replum invisible. Epicarp dull; monochrome; tan to brown; with surface texture uniform; brown to reddish brown pubescent and indurate, or glabrate, or glabrous; with hairs erect; with simple hairs; eglandular; without spines; smooth, or 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; surface not veined; 2-layered; without balsamic vesicles; with fibers; without reniform canals; with fibers scattered reticulate embedded in mealy tissue over solid layer (or fibers embedded in spongy tissue); ligneous. Endocarp present; visible; dull; opaque; mottled; brown to reddish brown; with mottling over seed chambers; with dark brown overlay; smooth and scurfy (dark colored under seeds, lighter colored around seeds); without adhering pieces of testa; subseptate to nonseptate; not exfoliating; remaining fused to mesocarp and epicarp; entire. Seed(s) 1–8; length parallel with fruit length, or transverse to fruit length (parallel according to length but transverse according to embryonic axis); touching; in 1 series. Funiculus 0.1–4 mm long; of 1 length only; flattened to thick; straight. Aril absent.

Seed: 12- 13–65 mm long; 11–45 mm wide; 1–27 mm thick; not overgrown; not angular; symmetrical, or asymmetrical; ovate to oblong, or irregular; compressed to flattened; 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; reddish to blackish brown to black; glabrous; smooth, or not smooth; with recessed features; obliquely striate (with large well defined interstices); 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; 0.1–5 mm long; with curved outline; elliptic to circular; apical at apex of radicle tip; raised to flush; not within corona, halo, or rim. Lens not discernible. Endosperm absent. Cotyledons not smooth; rugose (intruding corrugate cotyledons of M. acaciaefolium); both outer faces convex; both the same thickness; both more or less of equal length; not folded; margin not entire 180 degrees from base of radicle (wavy); similar at apex; completely concealing radicle, or partially concealing radicle (only tip exposed); notched at radicle; 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 to perpendicular to length of seed, or oblique to length of seed (seldom); without a joint evident between the radicle and the cotyledons. Radicle differentiated from cotyledon; centered between cotyledons. Plumule rudimentary; glabrous.

Distribution

Tropical America.

New World; Tropical United States to West Indies to Central America to South America; Peru, Brazil, Ecuador, and the Guianas.

Generic Notes

Cowan (1953) monographed the genus.

Tribal Notes

Tribe Detarieae

Bruneau et al. (2000) carried out extensive phylogenetic analyses of tribes Amherstieae and Detarieae. They concluded that they form a single monophyletic group. Therefore, they supported Polhill's (1995a, 1995b) decision to unite the two tribes.