These plants grow in swampy forests, and, being dioecious and varying much in the form of leaf in different individuals, are imperfectly known to botanists, only two species having been identified with certainty.
When the male and female flowers of a species are found on separate plants, the term dioecious is applied, as in Mercurialis and hemp; and when a species has male, female and hermaphrodite flowers on the same or different plants, as in Parietaria, it is polygamous.
Care should be taken in collecting charae to secure, in the case of dioecious species, specimens of both forms, and also to get when possible the roots of those species on which the small granular starchy bodies or gemmae are found, as in C. fragifera.
Spinifex, a dioecious grass, is widespread on the coasts of Australia and eastern Asia, forming an important sand-binder.
A conspicuous example of a dioecious plant is the common aucuba, of which for years only the female plant was known in Britain.
The genus is a member of the natural order Smiliaceae, and constitutes the tribe Smilacoidide, characterized by its climbing habit, net-veined leaves and dioecious flowers.
Long, obovate-lanceolate in shape and yellowish-green; the dioecious flowers, which are small and nearly of the same colour but,yellower, appear in February and March; the white berry when ripe is filled with a viscous semitransparent pulp (whence bird-lime is derived).
Smilacoideae are climbing shrubs with broad net-veined leaves and small dioecious flowers in umbels springing from the leaf-axils; the fruit is a berry.