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.

Ricinus

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.

Croton

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.

Acalypha

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.

Euphorbia