Samanea (Benth.) Merr., J. Wash. Acad. Sci. 6(2): 46. 1916.

Figs 253, 254

Pithecellobium sect. Samanea Benth., London J. Bot. 3: 197. 1844. Type: Pithecellobium saman (Jacq.) Benth. [≡ Mimosa saman Jacq. (≡ Samanea saman (Jacq.) Merr.)]

Type.

Samanea saman (Jacq.) Merr. [≡ Mimosa saman Jacq.]

Description.

Unarmed trees (Fig. 253A, D), some attaining great age, height, and crown width; brachyblasts absent. Stipules lanceolate, caducous. Leaves bipinnate, terminating in a pair of pinnae (Fig. 253C), extrafloral nectaries present; pinnae 3-6 (7) pairs, opposite; leaflets 3-9 pairs, opposite, obliquely oblong to rhombic obovate, inequilateral, pinnately veined. Inflorescences axillary umbelliform glomerules (Fig. 253B). Flowers dimorphic; peripheral flowers shortly pedicellate (Fig. 253E); calyx vase-shaped; corolla trumpet-shaped; androecium with (16) 20-36 stamens, the staminal tube included in the corolla, filaments pink or reddish, the basal portion sometimes white (Fig. 253E); pollen in 32-celled polyads and perforate tecta; ovary (sub)sessile, narrowly ellipsoid; central flower stouter and sessile with more numerous stamens. Fruit broadly linear, indehiscent (seeds released as the fruit decays or animal dispersed), straight or nearly so (Fig. 253F), compressed or plump, with an incrassate pericarp, thin glabrous or puberulent exocarp, a thick sweet nutritive pulpy mesocarp and a crustaceous-woody endocarp. Seeds oblong-ellipsoid, the testa hard, with an open U-shaped pleurogram.

Chromosome number.

2 n = 26 ( Samanea saman) (Goldblatt and Davidse 1977; Santos et al. 2012).

Included species and geographic distribution.

Three species, mostly circum-Amazonian in tropical continental Central and South America, native from El Salvador in Central America south eastwards through Venezuela, Colombia, Peru and Ecuador, to north-eastern Bolivia, southern, eastern and north-eastern Brazil, and Paraguay. Samanea saman is widely cultivated and partly naturalised as far north as Mexico, and long established in the West Indies in parks and gardens (Fig. 254). It is also widely planted in the Old World tropics as an ornamental, or plantation shade tree.

Ecology.

Seasonally dry deciduous to moist evergreen forest, woodland, and wooded grassland.

Etymology.

‘Saman’ is derived from the French Caribbean vernacular ‘zamang’ or 'rain tree’, the leaves fold up at dusk or at the approach of storms.

Human uses.

Widely planted pantropically for shade (especially coffee), preserved in pastures as cattle-shade, planted as an ornamental and for nutritious fruits (for animal fodder, human food and for beverages), also for medicine and timber (for a wide range of uses from construction and panelling to furniture and veneers), and for bee forage (Lewis and Rico Arce 2005).

Notes.

The species now included in Samanea were included in several different genera of the old sense tribe Ingeae. Nielsen (1981a) subsumed them into his broadly defined circumtropical genus Albizia Duraz. until the genus was reinstated by Barneby and Grimes (1996), who recognised three species, and provided a key to identify them.

Taxonomic references.

Barneby and Grimes (1996); Lewis and Rico Arce (2005).