Albizia is a genus of about 150 species, with a cosmopolitan distribution across tropical and subtropical areas. They are trees, shrubs or rarely climbers, typically unarmed, though the climbing species have recurved prickles by the leaf scars. Leaves are alter nate, bipinnate; foliar glands are present on the petiole and sometimes between or below the junctions of pairs of pinnae and/or pinnules; pinnules are opposite, petiolulate or sessile, small to large, often asymmetric, few to numerous; stipules small and caducous or, rarely, conspicuous and leaf-like (for example, A. chinensis Merr.). The inflorescences are axillary or terminal, heads or corymbs, which may be arranged in fascicles, panicles or rarely spikes or racemes; heads or corymbs may be dimorphic, with a single large central flower and adjacent smaller flowers. The flowers are hermaphrodite, sessile or pedicellate and (4–)5-merous. The calyx and corolla are often greatly reduced and have been largely replaced in the role of attractant by the numerous stamens. The fruit is a strap-shaped legume (pod), which may be dehiscent or indehiscent (Nielsen 1981, Chakrabarty & Gangopadhyay 1996).
Of all the numerous Albizia species, only A. julibrissin has become familiar in temperate gardens. It is a notable beneficiary of the currently warming climate and is now being grown over a much wider area than was previously thought possible. Provenance and selection for cold-hardiness are undoubtedly also factors in this, but warmer summers enable new wood to ripen more thoroughly and this in turn confers extra tolerance to frost. A notable new selection made in Japan is ‘Summer Chocolate’, with amazing dark purplish foliage. Its comparative hardiness is not yet known. In the southern United States the yellow-flowered A. lebbeck (L.) Benth. has become naturalised and is rather invasive in Florida, but is not hardy further north (Cook 2006).
From Bean's Trees & Shrubs
A genus of more than 100 species, all (save A. occidentalis of Mexico) confined to the Old World. It is closely related to Acacia, but differs in having the stamens united at the base. The generic name should be spelt with one z.