They are found in the Compoeitae (Cickoriaceae), Campanulaceae, Papaveraceae, Loheliaceae, Papayaceae, in some Aroideae and Musaceae, and in Euphorbiaceae (Manihot, Ilevea).
Amongst arboreous families Leguminosae and Euphorbiaceae are prominent; Hevea belonging to the latter is widely distributed in various species in the Amazon basin, and yields Para and other kinds of rubber.
In the Euphorbiaceae we have an excellent example of the gradual suppression of parts, where from an apetalous, trimerous, staminal flower we pass to one where one of the stamens is suppressed, and then to forms where two of them are wanting.
The similarity of certain xerophilous Euphorbiaceae to Cactaceae is a ready illustration of this phenomenon.
Manihot Glaziovii belonging to the Euphorbiaceae is the tree of N.E.