Albizia

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Albizia

Description

Shrubs, trees, or lianas, usually unarmed, the lianas being armed by an unpaired prickle from the base of the leaf-scar. Leaves bipinnate, not sensitive to the touch, rachis and pinnae with extrafloral nectaries; Stipules present, subular to linear or auriculate, often early caducous, in one species transformed into recurved thorns. Inflorescences consisting of pedunculate glomerules or corymbs which are either axillary or aggregated into terminal or axillary panicles; Flowers pentamerous, usually dimorphic (uniform in 5 species), the marginal flowers in each flowerhead bisexual, the central flower male and enlarged with a conspicuous nectary. Stamens numerous, united into a tube at the base; Ovary solitary, sessile or stipitate. Seeds circular, elliptic to oblong in outline, ± flattened, with a hard testa with pleurogram, wingless;

Distribution

Africa: present Asia-Tropical: Central and South America: present Madagascar: present Pantropical: present
Pantropical, with centres of speciation in Africa, Madagascar, Central and South America, c. 150 species in all; throughout Malesia, with 20 indigenous species. — .

Morphology

Several species have (flowering) glomerules with in the centre an enlarged flower. In the Malesian species with floral dimorphy the staminal tube is thicker and (strongly) exserted in the central flower, the ovary is sessile and surrounded by a ring-shaped nectary at the base. The central flower has as yet never been seen fruiting, and it is assumed that it attracts pollinators. In the descriptions only the marginal flowers have been described.

Taxonomy

In earlier papers [Nielsen (I.c. 1981); ] the reasons for the exclusion of sect. Lophantha and sect. Spiciflorae from the genus Albizia were given. It remains an open question whether the genera Cathormion and Sama- nea should be included, but until the American members of the genus have been revised they are kept separate.
The wide distribution of Albizia seems to indicate that it is an ancient genus, which, as Acacia, is well adapted to tropical seasonal climates.

Uses

Several species are good timber trees and some are important shade trees in coffee and tea plantations.

Citation

Benth. - in Trans. Linn. Soc. 1875: 557
Fourn. - in Ann. Sc. Nat. Bot. 1861: 161
Durazz. - in Opera Bot. 1985: 27
Taub. - in E. & P., Nat. Pflanzenfam. 3. 1891: 106
Benth. & Hook. f. - in Gen. Pl. 1865: 596
Nielsen - in Polhill & Raven, Adv. Legum. Syst. 1. 1981: 180
Hutch. - in Gen. Fl. Pl. 1964: 294