Leucaena

Taxonomy

Leucaena G. Bentham Nom. cons. J. Bot. (Hooker) 4: 416. Jun 1842.

Subfamily: Mimosoideae.
Phylogenetic Number: 2.3.30.
Tribe: Mimoseae.
Group: Leucaena.
Species Studied - Species in Genus: 9 studied; 22 in genus (Hughes, 1998aHughes, 1998a:
Hughes CE. 1998a. Leucaena, a genetic resources handbook. Trop. Forest. Pap. Commonw. Forest. Instit. 37:1&-274., 1998b).

Description

Fruit: A legume; unilocular; (7–)9–38 cm long (Hughes, 1998aHughes, 1998a:
Hughes CE. 1998a. Leucaena, a genetic resources handbook. Trop. Forest. Pap. Commonw. Forest. Instit. 37:1&-274., 1998b); (0.7–)0.9–3.6 cm wide (Hughes, 1998a, 1998b); 0.2–0.3 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 to curved; not plicate; not twisted; symmetrical; broadly linear to linear, or oblong; not inflated; compressed; without beak, or with beak; straight; with solid beak the same color and texture as fruit; short tapered at apex to tapered at apex, or rounded at apex; aligned with longitudinal axis of fruit; short tapered at base to tapered at base; aligned with longitudinal axis of fruit; with the apex and base uniform in texture; coriaceous to leathery, or chartaceous (rarely); seed chambers externally visible, or invisible; seed chambers with the raised seed chambers not torulose; margin irregularly slightly constricted to not constricted; margin slightly constricted along both margins; margin without sulcus; margin plain; wing(s) absent; stipitate, or substipitate; with the stipe 4–30 mm long; with all layers dehiscing; splitting along suture(s). Dehiscence of valves along both sutures (remaining attached to sutures); apical and down; passive, or active (in Leucaena confertiflora S. Zárate P. and L. cuspidata P.C. Standley); with valves twisting. Replum invisible. Epicarp glossy; monochrome; brown (to reddish, blackish or orangish brown); with surface texture uniform; glabrous to pubescent and indurate (densely); with hairs erect; with 1 type of pubescence; with pubescence uniformly distributed; with white simple hairs (straight), or complex hairs; with reddish scales; pliable; with hair bases plain; eglandular; without spines; not smooth; with elevated features; veined; reticulately veined; not tuberculate; exfoliating; without cracks; without embedded tissue, much thicker than epicarp, running from base to apex. Mesocarp absent. Endocarp present; visible; dull; opaque; mottled; tan; with mottling over seed chambers; with brown overlay; smooth; without adhering pieces of testa; subseptate to nonseptate; with septa thin (tissue paper-like), flexible; with septa eglandular; chartaceous to coriaceous; not exfoliating; remaining fused to epicarp; without wings; entire. Seed(s) 6–26; length transverse to fruit length to oblique to fruit length; neither overlapping nor touching; in 1 series. Funiculus 4.5 mm long; of 1 length only; thick; S-curved. Aril absent.

Seed: 5–11.8 mm long; 2.7–10.6 mm wide (Hughes, 1998a, 1998b); 1–2 mm thick; not overgrown; not angular; symmetrical; ovate to circular, or oblong; 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; glabrous; smooth, or not smooth; with elevated features and recessed features; bearing a raised line (more like a ridge from apex to middle of areola); shallowly pitted with small separate pits (especially outside of areola); osseous. Pleurogram present; 75–90 %. Pseudopleurogram absent. Fracture lines present. Rim absent. Wing(s) absent. Raphe not visible. Hilum present; visible; without faboid split; punctiform; subapical to radicle tip; flush; not within corona, halo, or rim. Lens discernible; 0.3–0.4 mm long; with margins straight, or curved; linear (and inconspicuous); elliptic (and conspicuous); not in groove of raphe; mounded; similar color as testa, or dissimilar color from testa; lighter than testa; tan to white; not within corona, halo, or rim. Endosperm present; thin to thick; 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; with lobes; with lobes not touching; 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; deflexed and parallel to cotyledon length; centered between cotyledons. Plumule moderately developed; glabrous.

Distribution

Mexico, West Indies, Central America, South America, and southern Texas, introduced elsewhere.

New World; Mexico, West Indies, Central America, South America, and United States (southern Texas, Colombia, Venezuela, and Peru in South America, and introduced elsewhere); Peru, Brazil, and the Guianas.

Worldwide crop.

Generic Notes