Prosopis
(an old Greek name used by Dioscorides for the Butter-bur). Including Algarobia. ORD. Leguminosae. This genus comprises about eighteen species of trees or shrubs, often armed with hooked prickles or stout, axillary spines, or with both, dispersed through the tropical and sub-tropical regions. Flowers small, in cylindrical spikes, or rarely in globose heads; calyx campanulate, shortly dentate; petals valvate. Leaves bipinnate, generally rigid, and of a glaucous hue, with only one or two pairs of pinnae, but with a considerable number of leaflets. The species are very rarely seen in cultivation, with the exception of P. siliquastrum, a nearly hardy tree, which thrives in sandy loam. Propagation is effected by rather firm young shoots, taken off close to the older stems, and inserted in sand, under a glass, in gentle heat. P. siliquastrum (Siliqua-podded). fl. white. l. with two or three pairs of pinnae, each pinna having numerous pairs of linear, obtuse leaflets. Spines stipular, twin, straight. h. 30ft. to 40ft. Chili, 1827.