321 genera, 7,770 species (including Phyllanthaceae) Distributed widely in tropical and subtropical regions, with few species in temperate regions.
Salient features:
Plants usually a milky latex, alternate leaves, flowers unisexual, carpels 3, ovary superior, 3-chambered, ovule with a caruncle.
Major genera:
Euphorbia (2100 species), Croton (720), Phyllanthus (500), Acalypha (350), Glochidion (300), Antidesma (140), Manihot (160), and Jatropha (140).
Description:
Herbs (some species of Euphorbia, Phyllanthus) shrubs (Acalypha), or trees (Hevea) with often milky or colored latex, sometimes succulent and cactus-like, usually poisonous.
Leaves:
alternate rarely opposite (some species of Euphorbia; Excoecaria) or whorled (Mischodon), some- times modified into spines, simple or palmate compound, venation pinnate or palmate, reticulate, stipules present, sometimes modified into spines (Euphorbia milii) or glandular, rarely absent.
Inflorescence
Inflorescence of various types, commonly a cup-shaped cyathium (Euphorbia) having a cup-shaped
involucre with usually 5 nectaries along the rim and enclosing numerous male flowers (arranged in scorpioid cymes, without perianth and represented by a single stamen) and a single female flower in the center sometimes a raceme (Croton) or panicle (Ricinus).
Flowers
Flowers are unisexual (monoecious or dioecious), actinomorphic, and hypogynous.
Perianth
Perianth usually with 5 tepals (representing sepals, petals absent), rarely 6 in two whorls (Phyllanthus) or absent (Euphorbia), petals usually absent but present in Jatropha and Aleurites, free or connate.
Androecium
Androecium with 1 stamen (Euphorbia), 3 with fused filaments (Phyllanthus), 5 (Bridelia) or many (Trewia), sometimes polyadelphous (or with repeatedly branched filaments) as in Ricinus, anthers bithecous (sometimes monothecous in Ricinus due to splitting of filament), dehiscence longitudinal.
Gynoecium
Gynoecium with 3 united carpels, carpels rarely 4-many, ovary superior, trilocular with 1-2 ovules in each chamber, placentation axile, styles usually 3.
Fruit
Fruit a schizocarpic capsule, a regma (Ricinus), rarely a berry or drupe (Bridelia); seed often with conspicuous fleshy outgrowth called caruncle, embryo curved or straight, endosperm abundant or absent.
Economic importance:
The family includes a number of valuable plants. Hevea brasiliensis (Para rubber tree) is the source
of natural rubber. Rubber is also obtained from Manihot glaziovii (ceara rubber). Thick roots of Manihot esculentus (cassava or tapioca) are an important source of starch in tropical regions. The leaves of Cnido-scolus chayamansa are used as vegetables.
The fruits of Antidesma bunias are also edible. Aleurites moluccana (candlenut tree) and A. fordii (Tung tree) are sources of oils used in the manufacture of paints and varnishes. An oil similar to tung is also obtained from the species of Vernicia. Castor oil obtained from Ricinus communis is used as purgative.
The common ornamentals include Euphorbia pulcherrima, E. milii, Acalypha hispida, Jatropha pand-uraefolia and Codiaeum variegatum. The fruit of Phyllanthus emblica (‘amla’) is very rich source of vitamin C. The greasy tallow surrounding the seeds of Sapium sebiferum (Chinese tallow tree) is used for
making soaps and candles.