Trees; branchlets green, short-lived, cylindrical, jointed, striate, photosyn-thetic; leaves whorled, reduced to lanceolate or subulate scales at each node; plants monoecious; flowers unisexual, in catkins; the male on the ends of branchlets, either the ordinary or special ones; male flower of a single stamen with a bract, these in whorls, the bracts connate; female catkins condensed, capitate, lateral, each flower in the axil of a bract, protected by 2 lateral bracteoles, with a bicarpellate ovary, one-celled, with 2 long stigmas, 2 ovules, one of which is abortive; the female catkin becoming large, the bracts becoming woody in fruit, forming a cone-like structure; fruit a 1-seeded, 1-winged samara. Casuarina the only genus.