Croton  

Trees, shrubs, herbs or climbers, dioecious or monoecious. Exudate (from cut stems) absent, or present, clear, yellow, orange or red. Unarmed or armed (stipules very rarely spine-like). Indumentum present (rarely almost absent), hairs lepidote (scales often shiny) and/or stellate. Stipules absent or present, free, simple, unlobed or lobed, margin entire or toothed (sometimes very deeply and finely), very rarely spine-like, leaf-like or not, with or without glands. Leaves usually distributed evenly along stem, rarely clustered towards twig tip, alternate, opposite or whorled, simple, unlobed or lobed, base symmetrical, margin toothed or entire, blade not pellucid-punctate, upper surface without glands, lower surface and margin with or without glands, glands present at leaf base/petiole apex; venation pinnate or with 3–7 strong veins from base; domatia very rarely present; stipel-like appendages absent*. Petiole present, occasionally absent or almost so, rarely swollen at base or apex, gland(s) present at apex. Inflorescence with axis, axillary or terminal, in branched clusters or groups, or spike- or raceme-like, bracts present, or apparently absent, leaf-like or not, with or without glands, green; pedicels absent or present, not articulated; flowers with radial or bilateral symmetry. Male flowers: sepals (3) 4–6; imbricate or valvate, free or partially fused, not enlarged relative to other floral parts, greenish; petals 0 or (3) 4–6, imbricate or valvate, free, greenish or white, hairy or not; disc outside the staminal whorl (extrastaminal), annular or comprised of distinct parts, or rarely disc 0; stamens 1–300, free; anther without conspicuous modification, anther in bud inflexed; pistillode absent. Female flowers: sepals (3)4–10, imbricate or valvate, free or partially fused, sometimes enlarged relative to other floral parts, persistent or falling early, greenish; petals 0 or 4–6 in female flowers, imbricate or open (not overlapping), free or partially fused, hairy or not, greenish or white; disc surrounding the ovary, annular or comprised of distinct parts; ovary locules 1–3(4), ovules per locule 1; styles 1–4, free* or partially fused*, style entire or divided, styles or stigmas flat or not flat*, surface smooth or papillose; staminodes absent or present. Fruit dehiscent or indehiscent, smooth, with longitudinal ribs or crests*, bristly, tuberculate, warty, or longitudinally grooved, glabrous or hairy, greenish to brown (probably other colours too); seed with or without a caruncle, sometimes partially covered by an aril-like structure, otherwise seed without appendage, covering or membraneous layer*, not fleshy; embryo not minute, narrow, cotyledons needle-like or leaf-like.

An asterisk * indicates a state has been assumed but not yet confirmed.

About 800 spp.

With thanks to Paul Berry (University of Michigan) for help with this genus.

See: Paul E. Berry, Inês Cordeiro, Alex C. Wiedenhoeft, Maria Amélia Vitorino–Cruz, Letícia Ribes de Lima (2005). "Brasiliocroton, a New Crotonoid Genus of Euphorbiaceae s.s. from Eastern Brazil". Systematic Botany 30 (2): 357–365.