This is a predominantly tropical family with about 6,500 species. In some genera a milky (or colored) latex is produced, as in the largest genus, Euphorbia.
1. Leaves peltate, all but the smallest blades over 10 cm broad, palmately veined and ± deeply divided into acute lobes; inflorescence a large terminal raceme or panicle.
1. Leaves not peltate, the blades less than 5 cm broad, pinnately veined (or 3-veined at the base), unlobed; inflorescence various, usually ± umbellate or axillary.
2. Stem and leaves with some (or all) hairs forked or stellate.
2. Stem and leaves glabrous or with only simple hairs.
3. Plant with watery sap; flowers not in cyathia, but pistillate flowers enclosed in a deeply lobed foliaceous bract; stem pubescent with incurved hairs.
3. Plant with milky juice; flowers grouped into cup-like cyathia with a central stalked pistillate flower and several staminate flowers consisting of 1 stamen each; stems glabrous or variously pubescent.