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Key to Euphorbiaceae

Euphorbiaceae

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1 Plant a twining vine (herbaceous or woody at base) to 5 m long; stem with stinging hairs; [subfamily Acalyphoideae]
1 Plant not twining; instead a tree, shrub, or herb (or weakly twining in some Tragia, but then less than 1 m long); stem either armed with stinging hairs, or not armed.
  2 Shrub or tree (woody).
    3 Leaves entire.
      4 Hairs of vegetative parts of the plant (especially the leaf undersurface) present and either 2-branched, stellate, or modified into lepidote scales (use 10× or more magnification); [subfamily Crotonoideae].
      4 Hairs of vegetative parts of the plant (especially the leaf undersurface) absent or unbranched (simple) (use 10× or more magnification).
        5 Flowers enclosed in a cyathium; plant with copious white latex; [subfamily Euphorbioideae]
        5 Flowers not enclosed in a cyathium; plant either with or without white latex (the sap clear to whitish or absent).
          6 Leaf blades 1-1.5× as long as wide; [exotic trees].
(c) Girdhari, Sayee - CC-BY
             7 Petioles 9-19 cm long; [subfamily Crotonoideae]
(c) Bradley, Keith
             7 Petioles 2-6 cm long; [subfamily Acalyphoideae]
          6 Leaf blades 1.5-5× as long as wide; native or exotic shrubs or, rarely, small trees.
               8 Leaves usually conspicuously variegated; [waif, se. FL]
               8 Leaves not variegated; [widespread native and non-natives]
                 9 Sepals absent; latex watery; leaf margins obscurely gland-toothed; [subtropical hardwood hammocks of far southern FL]; [subfamily Euphorbioideae]
                 9 Sepals present; latex absent or watery; leaf margins entire; [various habitats and collectively widespread].
                   10 Latex colorless to whitish, watery; capsules ovoid or ellipsoidal; [FL peninsula and s. TX]; [subfamily Crotonoideae]
                   10 Latex absent; capsules subglobose; [collectively widespread in our region].
                     11 Leaves palmately veined at base; inflorescence bracts not subtended by glands; [s. TX and southwards]; [subfamily Acalyphoideae]
                     11 Leaves pinnately veined; inflorescence bracts with 2 subtending glands; [widespread from NC to FL west to AR and e. TX]; [subfamily Euphorbioideae]
                       12 Plants hairy with 2-branched hairs (malpighiaceous trichomes); [subfamily Acalyphoideae]
                          13 Leaves palmately lobed, margins entire, crenate, or serrate (Mallotus often with at least a few obscurely lobed leaves).
                              15 Plants pubescent, often with a mix of unlobed to obscurely 3-lobed leaves, the lobes not extending deeply and the blades not star-shaped; [waif, FL panhandle]
                              15 Plants glabrous, the leaves conspicuously 7-12 palmately lobed, appearing almost star-shaped; [widespread non-native]
                                         20 Leaf blades obovate, 2-3× as long as wide, with a rounded apex; petiole < 0.2 cm long; fruit a capsule, 1.0-1.3 cm in diameter; [TX]; [subfamily Acalyphoideae]
                                         20 Leaf blades ovate, 1-2× as long as wide, with an acute apex; petiole 1-6 cm long; fruit a drupe, 1.5-2.5 cm in diameter; [FL]; [subfamily Euphorbioideae]
  2 Herb.
(c) Hernández, Alexis López - CC-BY
                                             22 Plants with a prominent, round woody shallow subterranean caudex to 13.5 cm in diameter; [subfamily Crotonoideae]
                                               23 Leaves peltate; plant glabrous; stamens 100-1000; [subfamily Acalyphoideae]
                                                              30 Flowers in terminal spikes; stout perennial with several to many stems arising from a subterranean crown; [subfamily Euphorbioideae]
                                                              30 Flowers strictly axillary or both axillary and terminal, in small clusters, racemes, or spikes; finer perennial or annual, not typically with > 1 stem arising from a subterranean crown; [subfamily Acalyphoideae]
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Key G2: woody plants with alternate, simple, palmately lobed leaves

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      4 Tendrils branched, leaf-opposed; leaves mostly 5-7-lobed, the margins also serrate or dentate
      4 Tendrils simple (though paired in Smilax in SMILACACEAE), axillary; leaves 3-lobed, the margins entire, serrulate, or prickly.
        5 Leaves longer than wide, entire or prickly-margined; stems usually obviously armed with prickles; flowers 6-merous, greenish, in umbels borne in leaf axils; tendrils stipular, 2 per leaf axil, adnate to the petiole basally
        5 Leaves wider than long, entire or serrulate; stems not armed; flowers 5-merous, blue-purple or yellow, solitary or in small fascicles in leaf axils; tendrils 1 per leaf axil
1 Trees or shrubs.
             7 Leaves > 3 dm long and wide; tree monopodial, with a single, unbranched stem (rarely with a few branches).
               8 Leaf lobes > 15, not sublobed; venation of each lobe parallel; fruit a drupe, with 1 seed; [Monocots]
               8 Leaf lobes < 13, most of these sublobed; venation of each lobe pinnate; fruit either a many-seeded berry or a single-seeded nutlet; [Eudicots].
                 9 Petiole attachment marginal; leaf lobes mostly sublobed; fruit a large berry, with many seeds
                 9 Petiole attachment peltate; leaf lobes not sublobed; fruit an nutlet, single-seeded
             7 Leaves < 3 dm long and wide; tree branching; [Eudicots].
                   10 Leaves 2-lobed (deeply notched at the apex), each lobe separated by the midvein, asymmetrical; [peninsular FL and s. TX]
                   10 Leaves 3-5 (-7) lobed; [collectively widespread].
                     11 Leaf blades (3-) 5 (-7) lobed, to 15 cm wide and long, each lobe finely serrate-crenate (>3 teeth per cm of margin) and rarely with a small sub-lobe; multiple fruit spherical and spiky, consisting of multiple bird-beak-like loculicidal capsules; buds axillary
                     11 Leaves 3 (-5)-lobed, to 35 cm wide and long, each lobe coarsely toothed or sublobed, the teeth or sublobes (at most 1-2 per cm of margin) attenuate-acuminate; multiple fruit spherical and merely rough on the surface, consisting of multiple achenes with tawny bristles; buds infrapetiolar (completely hidden in the swollen petiole base)
                                16 Leaves 10-30 cm long and wide; fruit a berry; inflorescence of solitary to a few flowers, or a raceme