An order of flowering plants, division Magnoliophyta (Angiospermae), in the subclass Rosidae of the class Magnoliopsida (dicotyledons). The order consists of the large family Euphorbiaceae (about 7500 species) and 3 small satellite families which have fewer than 100 species among them. The Euphorbiales are a group of few-ovulate, mostly simple-leaved Rosidae in which the flowers have become unisexual and then undergone further reduction accompanied by aggregation. The trend toward reduction and aggregation culminates in the very large genus Euphorbia, with perhaps 1500 species, in which the pseudanthium has a pistillate flower consisting of a naked, tricarpellate pistil surrounded by several staminate flowers, each of which consists of a single stamen. The illusion that this cluster constitutes a single flower is fostered also by the cup-shaped involucre which often bears showy, petallike appendages. The Christmas poinsettia (E. pulcherrima) and the para rubber tree (Hevea brasiliensis) are well-known members of the Euphorbiaceae. Many African euphorbiads are spiny stem-succulents which resemble cacti in habit. Aside from the pronounced floral differences, the euphorbiads have a milky juice, which the cacti do not.