EUPHORBIA, in botany, a large genus of plants from which the family Euphorbiaceae takes its name. It includes about 75o species and is of almost world-wide distribution. It is repre sented in Great Britain and North America by the spurges— small, generally smooth, herbaceous plants with simple leaves and inconspicuous flowers arranged in small cup-like heads (cyathia). The cyathium is characteristic of the genus, and consists of a num ber of male flowers, each reduced to a single stamen, surrounding a central female flower which consists only of a stalked pistil; the group of flowers is enveloped in a cup formed by the union of four or five bracts, the upper part of which bears thick, conspicu ous, gland-like structures, which in exotic species are often bril liantly coloured, giving the cyathium the appearance of a single flower (e.g., the so-called Poinsettias). Another characteristic is the presence of a milky juice, or latex, in the tissues of the plant. In one section of the genus the plants resemble cacti, having a thick succulent stem and branches with the leaves very small or reduced to a small wart-like excrescence, with which is generally associated a tuft of spines (a reduced shoot) . These occur in the warmer parts of the world and are essentially dry country or desert vegetation.