EUPHORBIACEAE

the spurge family of flowering plants, in the order Euphorbiales, containing some 7,500 species in 275 genera. Many members are important food sources; others are useful for their waxes and oils and as a source of medicinal drugs; dangerous for their poisonous fruits, leaves, or sap; or attractive for their colourful bracts (leaflike structures located just below flower clusters) or unusual forms. Although species of the family grow throughout the world, except in cold alpine or arctic regions, most of them are found in temperate and tropical regions. The family consists of annual and perennial herbs and woody shrubs or trees, rarely climbers. Flowers are of one sex, with male and female flowers usually borne on the same plant. Petals are rarely present. Flowers of Euphorbia are in cup-shaped clusters called cyathia, each of which seems to be a single female flower, consisting of a single pistil surrounded by several male flowers, each of which has a single stamen. These clusters of reduced flowers are enclosed by an involucre (whorl) of bracts (modified leaves) that resembles a corolla, or whorl of flower petals. Male flowers of the other genera have one to many stamens, free or joined. Female flowers have three-chambered ovaries that are superior (that is, above and not enclosed by other flower parts). There are as many styles as there are ovary cavities. The fruit is a three-chambered capsule. Leaves are usually simple and are alternate (or rarely opposite or whorled) in arrangement along the stems. The stems of many species contain a milky latex. Members of the family known for beauty or usefulness include the largest genus, Euphorbia, commonly called spurge (q.v.), with a wide range of succulent plants from lawn weeds to cactuslike plants; ornamentals such as Codiaeum, sandbox tree (Hura), copperleaf (Acalypha), Phyllanthus, redbird cactus (Pedilanthus), Jatropha; and economically important plants such as castor-oil plant (Ricinus communis), croton (Croton tiglium), Omphalea, cassava (Manihot esculenta), rubber (Hevea), tung tree (Aleurites; a source of candlenut oil), and tallow tree (Sapium). The manchineel tree (Hippomane mancinella) bears poisonous fruits, and mercury (Mercurialis; see ) is a weed in many areas.