Common Name: SPURGE FAMILY
Habit: Annual to shrub, tree [vine, cactus-like succulent]; monoecious or dioecious; sap clear or milky. Stem: generally branched [fleshy or spiny]. Leaf: generally simple, alternate to whorled, generally stipuled, sessile or petioled; blade entire, toothed, or lobed. Inflorescence: flowers solitary or in terminal or axillary cymes, racemes, spikes, or panicles, or (in Euphorbia) 1° inflorescence a compact, flower-like cyathium with much-reduced flowers enclosed within an involucre of fused bracts, cyathia terminal or axillary, 1 or in cyme-like arrays. Flower: unisexual, +- radial; sepals 0 or 2--6, free or fused; petals generally 0(5); stamens 1--many, free or filaments fused; ovary superior, chambers (1)3(4), styles free or fused, undivided, forked, or variously lobed. Fruit: generally capsule that splits into mericarps that then dehisce, releasing seeds. Seed: 1 per chamber; knob-like appendage sometimes present at attachment scar.
Genera In Family: 217 genera, 6000+ species: +- worldwide especially tropics; some cultivated (Aleurites, tung oil; Euphorbia species; Hevea, rubber; Ricinus). Toxicity: Many species +- highly TOXIC, due primarily to latex, especially if eaten or in contact with skin, eyes. Note: Eremocarpus moved to Croton, Tetracoccus moved to Picrodendraceae for TJM2; Chamaesyce moved to Euphorbia here (key to genera revised by Thomas J. Rosatti).
eFlora Treatment Author: Mark H. Mayfield & Grady L. Webster, except as noted
Scientific Editor: Bruce G. Baldwin.

Common Name: SPURGE
Habit: Annual to shrub [tree; fleshy, +- cactus-like], glabrous or hairy; sap milky; generally monoecious. Stem: prostrate to erect, generally < 1 m; branches arrayed around main stem(s) in 3-dimensions or 2-ranked, resulting in 2-faced stems with adaxial leaf faces all displayed to top side and abaxial leaf faces to bottom side. Leaf: proximal cauline, alternate or opposite, +- sessile to petioled; distal-most cauline in some species whorled, subtending umbel-like cluster of inflorescence branches, leafy bracts distal to whorled leaves generally opposite (whorled); stipules 0, gland-like, thread-like, or scale-like, free or fused, entire to divided; blade entire or toothed (pinnately lobed), base symmetric or asymmetric. Inflorescence: 1° inflorescence a cyathium, resembling a flower; cyathia 1--many, stalked or sessile, terminal (axillary), in generally leafy-bracted cyme-like arrays; cyathium a compact unit comprising an involucre of 5 fused bracts enclosing 1--many reduced staminate flowers and 1(0) pistillate flower; involucre generally 1--5 mm, bract tips alternate with 1--5 nectary glands (derived from modified stipules of involucre bracts), these transversely crescent-shaped or oblong to +- round, flat to cup-like, entire, toothed, or with 2 horn-like lobes, with or without distal, white to pink or red, flat, petal-like appendages; bractlets within involucre membranous or thread-like, often fringed. Staminate Flower: (1--4)5--many, generally in 5 clusters around pistillate flower (this difficult to observe); calyx 0; each staminate flower a single stamen jointed to tip of a thread-like pedicel; pedicel persistent, stamen deciduous after pollen released. Pistillate Flower: (0)1, central, stalked; calyx 0; ovary chambers 3, styles 3, free or fused at base, undivided or +- deeply forked. Fruit: stalk generally elongating, generally curved, pushing developing fruit from involucre; capsule +- spheric to ovoid or oblong, in ×-section +- round to 3-lobed or -angled. Seed: +- round or +- 3- or 4-angled (flattened) in ×-section, smooth or sculptured; knob-like appendage at attachment scar present or 0.
Etymology: Euphorbus, physician to the King of Mauritania, 1st century Note: Forms monophyletic group with Chamaesyce, included here. Euphorbia serrata L. considered extirpated from California; 2003 report that Euphorbia exigua L. is possibly naturalizing as yet unconfirmed; Euphorbia marginata Pursh occasionally persisting from gardens, but recent records lacking. Euphorbia graminea Jacq. an urban weed. For fruit, seeds, "in ×-section" indicated only if not lobed or angled.
eFlora Treatment Author: David J. Keil, Thomas J. Rosatti, Mark H. Mayfield & Daryl Koutnik
Reference: Horn et al. 2012 Molec Phylogen Evol 63:305--326
Unabridged Reference: Wheeler 1936 Bull S Calif Acad Sci 35:127--147