Fig. 459.—Diagram of an inflorescence (cyathium) of Euphorbia with 3 floral-leaves, m, n, o, supporting other cyathia which are subtended by 2 floral-leaves (bracteoles; m, n). 1–5, the involucral leaves in their order of development; the shaded portions are the crescentic glands.
Fig. 460.—Euphorbia lathyris: A an (entire) inflorescence (cyathium); B the same after the removal of the involucre.
Fig. 461.—Anthostema: ♂- (A) and ♀-(B) flowers; p the perianth; ar the node; o the ovule.
205 genera; more than 3,000 species; especially in the Tropics.—Many are used on account of the oil, and of the pungent (aperient, poisonous, anthelmintic, etc.) properties in the latex or the seeds. Officinal: “Cascarilla-bark” of Croton eluteria; the fatty oil of the seeds of Croton tiglium (Trop. Asia); “Castor oil” from Ricinus communis (Africa, and cultivated in all warm climates throughout the world); the glandular hairs of Mallotus philippinensis (“Kamala”); this also yields a red dye. Gum “Euphorbium” is the hardened (resinous) latex of the Cactus-like Euphorbia resinifera (Morocco).—Nutritive plants: Manihot utilissima and other species (Maniok, Am.). Their large, farinaceous roots form a very important article of food in the Tropics (Cassava-flour, Tapioca or Brazilian arrowroot). The fresh latex of the root in some species is a powerful poison; but the poisonous properties are diminished by roasting or cooking. Caoutchouc is obtained from Siphonia elastica (Trop. S. Am.). The vegetable tallow of the Chinese tallow-tree (Stillingia sebifera) is used in large quantities in soap factories. An indigo-like dye is obtained from Crozophora tinctoria, and is also found in Mercurialis perennis. Shellac is obtained from Aleurites laccifera. Ornamental plants: Acalypha, Croton, Dalechampia.—Hippomane is poisonous.
Order 2. Buxaceæ. This order differs from the Euphorbiaceæ in having the micropyle turned inwards; the ♂-flower has a 4-partite perianth and 4 stamens; the ♀-flower a 6-partite perianth and 3 carpels. Capsule with loculicidal dehiscence, the inner layer being detached elastically from the outer.—30 species. Shrubs without latex and with evergreen leaves.—Buxus sempervirens (Box) is an ornamental shrub (poisonous); it has a very hard and valuable wood which is used for wood-engraving and carving.
Figs. 462–464. Callitriche stagnalis.
Fig. 462.—♂-flower with the 2 bracteoles and the solitary stamen.