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Key to families | Table of families and genera

Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.



Mark H. Mayfield & Grady L. Webster, except as noted

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.
217 genera, 6000+ species: ± worldwide especially tropics; some cultivated (Aleurites, tung oil; Euphorbia species; Hevea, rubber; Ricinus). Many species ± highly TOXIC, due primarily to latex, especially if eaten or in contact with skin, eyes. [Yang et al. 2012 Taxon 61:764–789] Eremocarpus moved to Croton, Tetracoccus moved to Picrodendraceae for TJM2; Chamaesyce moved to Euphorbia here (key to genera revised by Thomas J. Rosatti). —Scientific Editor: Bruce G. Baldwin.

Key to Euphorbiaceae

1. Inflorescence a compact, flower-like cyathium comprising an involucre of fused bracts that encloses a cluster of 1-stamened staminate flowers and 1 pistillate flower; involucre margin bearing 1–5 nectary glands, these sometimes bearing petal-like appendages ..... EUPHORBIA

1' Inflorescence not a cyathium, not flower-like; pistillate and staminate flowers generally ± separated, not enclosed in an involucre; stamens 2–many per staminate flower

2. Leaves opposite ..... MERCURIALIS

2' Leaves alternate

3. Leaf peltate, blade palmately veined and lobed, 1–5 dm; inflorescence a panicle, terminal ..... RICINUS

3' Leaf not peltate, blade pinnately veined, entire or toothed, generally << 1 dm; inflorescences various

4. Petals present ..... DITAXIS

4' Petals 0

5. Stem and leaf hairs stellate

6. Leaf margin bluntly toothed; stipules persistent; staminate inflorescence axillary ..... BERNARDIA

6' Leaf margin entire; stipules inconspicuous; staminate inflorescence terminal or axillary ..... CROTON

5' Stem and leaf hairs 0 or unbranched

7. Bracts subtending pistillate flowers leaf-like, toothed, > fruit ..... ACALYPHA

7' Bracts subtending pistillate flowers 0 or scale-like, entire, << fruit

8. Leaves with stinging, nettle-like hairs; stamens 3–6; base of pistillate bracts without glands; stem sap clear ..... TRAGIA

8' Leaves ± glabrous or glaucous; stamens 2–3; base of pistillate bracts with 2 large glands; stem sap milky or clear

9. Annual or perennial herb; stamens 2; seeds 2–3.5 mm ..... STILLINGIA

9' Tree; stamens 2–3; seeds 6–9 mm ..... TRIADICA


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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