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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].
             7 Petioles 9-19 cm long; [subfamily Crotonoideae]
             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.
                                             22 Plants with a prominent, round woody shallow subterranean caudex to 13.5 cm in diameter; [subfamily Crotonoideae]
                                                              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]

Key to Stillingia

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1 Staminate flowers 1 at each node of the inflorescence; caruncle of the seed minute; [s. and c. TX, barely in our area]
1 Staminate flowers in 3-15-flowered cymules at each node of the inflorescence; caruncle of the seed either minute, or white, broadly crescent-shaped, and > 1 mm wide; [collectively fairly widespread in our area].
  2 Stems woody, solitary at base, from a taproot; (aerial) stems freely sympodially branched in the upper half to third of the plant, the whole plant appearing candelabra-like with age; the aerial branch system perennially developing by extension growth; leaves linear to lanceolate or narrowly elliptic, widest at middle or towards the base, clustered toward the branch tips; caruncle of the seed (typically) minute, exposing an inverted U-shaped hilar scar; [of pineland ponds and other aquatic habitats where the soil is inundated for at least four months of the year]
  2 Stems herbaceous, several from the crown of a woody rhizome; aerial stems not or little (sympodially) branched; aerial branches persisting for only a single growing season; leaves linear, elliptic, oblanceolate, or narrowly obovate, widest near the midpoint or towards the apex, stems appearing evenly leafy; caruncle of the seed white, broadly crescent-shaped, > 1 mm wide, largely concealing the hilar scar; [mostly of dry habitats, or mesic to wet pinelands that are only sporadically inundated].
    3 Leaf teeth with prominently blackened tips; leaf blades of mid to upper stem 3-6 (-10) mm wide; [rocky calcareous soils in OK and TX]
    3 Leaf teeth with tips not strongly contrasted in color from that of the mature leaf blade; leaf blades of mid to upper stem 2-30 mm wide; [widespread in our area].
      4 Leaf blades > 9 mm wide at widest point, L/W ratio (1.3-) 2.5-5.7 (-8.1), frequently broadest towards the tip; median bract subtending the pistillate cymule typically elliptic and the apex not clearly differentiated in shape; [widespread in our region, from se. VA to s. FL, westwards to OK, and TX]
      4 Leaf blades < 9 mm wide at widest point (typically 3.4-6.2 mm wide), L/W ratio (7-) 8.2-15.6 (-22), typically broadest near the middle; median bract subtending the pistillate cymule with a caudate-acuminate apex; [endemic in c. & s. FL]