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]

    3 Leaves crenate, serrate, and/or palmately lobed.

                       12 Plants hairy with 2-branched hairs (malpighiaceous trichomes); [subfamily Acalyphoideae]

                       12 Plants either glabrous or hairy with simple or stellate trichomes.

                          13 Leaves palmately lobed, margins entire, crenate, or serrate (Mallotus often with at least a few obscurely lobed leaves).

                            14 Petals absent; inflorescence a panicle; leaf lobe margins crenate to serrate; [subfamily Acalyphoideae].

                              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]

                            14 Petals present; inflorescence a cyme or dichasium; leaf lobe margins entire or serrate; [subfamily Crotonoideae].

                                16 Shrub or tree; inflorescence a fascicle or cyme; capsule ellipsoidal

                                16 Tree; inflorescence a dichasium; capsule subglobose

                          13 Leaves unlobed, margins serrate or crenate (obscurely crenate in Hippomane and Adelia).

                                  17 Leaves 8-20× as long as wide (lanceolate to linear); petiole with 0 or 2 glands at summit.

                                    18 Petiole with 2 glands at summit; [exotic, on ballast in Pensacola, FL]

                                    18 Petiole lacking 2 glands at summit; [native, widespread in our area]

                                  17 Leaves 1-3× as long as wide (elliptic, ovate, or obovate); petiole with 0 or 1 gland at summit.

                                       19 Lower leaf surface densely stellate-pubescent; leaf strongly toothed; [TX]; [subfamily Acalyphoideae]

                                       19 Lower leaf surface glabrous; leaf entire, obscurely crenate, or serrulate.

                                         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.

                                           21 Leaves palmately deeply divided into 3-many lobes.

                                             22 Plants with a prominent, round woody shallow subterranean caudex to 13.5 cm in diameter; [subfamily Crotonoideae]

                                             22 Plants lacking a prominent subterranean caudex.

                                               23 Leaves peltate; plant glabrous; stamens 100-1000; [subfamily Acalyphoideae]

                                               23 Leaves cordate to truncate or rounded at base; plant glabrous, stellate, or with conspicuous stinging trichomes; stamens 8-15; [subfamily Crotonoideae].

                                                 24 Plant with stinging trichomes; stamens connate

                                                 24 Plant lacking stinging trichomes; stamens separate.

                                                    25 Latex clear; pubescence stellate

                                                    25 Latex white; pubescence absent or of non-stellate hairs

                                           21 Leaves generally not lobed, entire or serrate (rarely pinnately lobed in Euphorbia).

                                                      26 Plants hairy with stellate hairs and/or scales; [subfamily Crotonoideae]

                                                      26 Plants glabrous or hairy with simple or 2-branched hairs.

                                                        27 Plants hairy with 2-branched hairs (malpighiaceous trichomes); [subfamily Acalyphoideae]

                                                        27 Plants glabrous or hairy with simple hairs.

                                                          28 Flowers enclosed in a cyathium; plant (fresh) with copious white latex; [subfamily Euphorbioideae]

                                                          28 Flowers not enclosed in a cyathium; plant (fresh) with or without white latex.

                                                            29 Capsules bearing numerous horned appendages; [uncommon non-native, wc. FL]

                                                            29 Capsules variously shaped, but lacking conspicuous horned appendages; [widespread native and non-natives]

                                                              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]

                                                                 31 Leaves opposite; carpels 2

                                                                 31 Leaves alternate; carpels 3 (sometimes fewer by abortion).

                                                                   32 Pistillate flowers subtended by a conspicuous leafy bract

                                                                   32 Pistillate flowers lacking a leafy bract.

                                                                     33 Plant lacking stinging trichomes; styles deeply multifid; [wetland habitats]

                                                                     33 Plant with stinging trichomes; styles undivided; [upland habitats]

1 Subshrubs or dwarf shrubs, aboveground stems creeping or erect, < 15 cm tall; leaves evergreen.

  2 Leaves 1.5-3 cm wide, coarsely toothed; flowers lacking sepals and petals; [exotic species, sparingly naturalized or spreading in suburban situations]

  2 Leaves < 1.5 cm wide, finely toothed or entire; flowers with sepals and petals; [native species, collectively widespread and common].

    3 Leaves fleshy, terete in ×-section; petals 5, bright pink

    3 Leaves flat, not fleshy; petals white or pale pink.

      4 Leaves < 2.5 mm wide; corolla with petals distinct; plant creeping

      4 Leaves > 5 mm wide; corolla with petals fused (distinct in Chimaphila); plant creeping or erect

1 Shrubs, aboveground stems erect, > 30 cm tall; leaves evergreen or deciduous.

        5 Inflorescence an involucrate (composite) head subtended by phyllaries, the heads solitary or many and variously arrayed in secondary inflorescences, the ovary inferior, the corolla connate and tubular at least basally, the calyx absent, the stamens 5, the fruit a cypsela

        5 Inflorescence, flower, and fruit structure various, but not with the combination of features as above.

          6 Leaves evergreen. {add to 6a Ardisia in PRIMULACEAE, Rhaphiolepis in ROSACEAE, Camellia in THEACEAE, Ochna in OCHNACEAE}

             7 Leaves glandular-punctate on one or both surfaces with golden-yellow glands; flowers unisexual, lacking a perianth (arranged in axillary catkins); fruit a pale gray, waxy drupe with a single seed

             7 Leaves not glandular punctate; flowers bisexual or unisexual, with a white, pink, or yellow perianth; fruit various: a red, blue, or black drupe, a berry with several seeds, or a capsule.

               8 Petals connate, flowers urceolate (ERICACEAE) or rotate, white to pale pink; flowers bisexual; fruit a drupe (Ehretia in EHRETIACEAE), OR a capsule or berry (ERICACEAE)

                 9 Flowers rotate, fragrant, the petals white, arranged primarily in terminal cymes; fruit an orange or yellow drupe, each bearing 2 hemispheric nutlets (these each also composed of 2 seeds, thus the fruit bearing 4 seeds)

                 9 Flowers urceolate, fragrant or not, the petals white to pale pink, variously arranged in terminal or axillary inflorescences (occasionally solitary in axils); fruit either a capsule or a red, blue, or black berry

               8 Petals distinct, yellow or white; flowers unisexual or bisexual; fruit either a black or red drupe with several pyrenes, a red berry with several seeds, or red or black pomes.

                   10 Plants with nodal, simple or tripartite thorns; flowers bisexual, with a yellow perianth; fruit a red berry with several seeds

                   10 Plants lacking thorns; flowers unisexual or bisexual, with a white perianth (yellow or red in Ochna); fruit either a black or red drupe with several pyrenes or a red or black pome.

                     11 Petals yellow, clawed; sepals red and forming a persistent red receptacle (torus) bearing numerous blackened drupes.

                     11 Petals white, not clawed; sepals not bright red nor persistent, the fruit a drupe or pome.

                       12 Flowers unisexual; fruit a black or red drupe with several pyrenes

                       12 Flowers bisexual; fruit a red or black pome

          6 Leaves deciduous {add [Fagaceae]}.

                          13 Plants with nodal, simple or tripartite thorns; leaf teeth spinulose

                          13 Plants lacking thorns; leaf teeth acute, blunt, rounded, or callus-tipped, but not spinulose.

                            14 Leaf blade bases conspicuously oblique-cordate or angled-truncate.

                              15 Leaves crenate-wavy, with 1-2 teeth per cm of leaf margin; pubescence of leaves and stems stellate

                              15 Leaves crenate or serrate, but usually not wavy, pubescence of leaves and stems simple {add to key; verify}

                            14 Leaves crenulate, serrate or serrulate, with >2 teeth per cm of leaf margin; leaves cuneate, rounded, or subcordate at base, not oblique; pubescence of leaves and stems absent or simple.

                                16 Leaves prominently 3-veined from the base.

                                  17 Ovary 5-locular; stamens many or 5, fused or separate; fruit a 5-valved capsule or of 5 mericarps; flowers yellow or pink, or white with a pink blaze

                                  17 Ovary 3-locular; stamens 5, separate; fruit a 3-valved capsule or drupe; flowers white or pale green

                                16 Leaves pinnately veined.

                                    18 Flowers in catkins; perianth absent or very small; fruit a 1-seeded nut, samara, or waxy drupe (capsule in Salix in SALICACEAE).

                                       19 Leaves > 4 cm wide, lacking punctate glands; fruit a 1-seeded nut or samara

                                       19 Leaves < 3 cm wide, either punctate-glandular on one or both surfaces or lacking punctate glands; fruit a 1-seeded waxy drupe or a capsule.

                                         20 Leaves punctate-glandular on one or both surfaces; fruit a 1-seeded waxy drupe.

                                         20 Leaves lacking punctate glands; fruit a capsule.

                                    18 Flowers arrayed variously, but not in catkins; perianth present, conspicuous; fruit a 1-many-seeded capsule, pome, berry, or follicle.

                                           21 Ovary inferior; fruit fleshy and indehiscent, a berry or pome.

                                             22 Fruit a berry; leaves lacking stipules

                                             22 Fruit a pome; leaves usually prominently stipular

                                           21 Ovary superior; fruit either dry and dehiscent, a capsule or an aggregate of follicles or achenes, or fleshy and indehiscent, a drupe with 4-8 pyrenes.

                                               23 Flower apocarpous; fruit an aggregate of follicles or achenes

                                               23 Flower syncarpous; fruit either a capsule or a fleshy drupe.

                                                 24 Ovary 1-carpellate; fruit a 1-seeded drupe

                                                 24 Ovary 2-8-carpellate; fruit either a capsule or a drupe with 4-8 pyrenes

                                                    25 Ovary 2-8-locular; fruit fleshy and indehiscent, a drupe with 2-8 pyrenes; flowers mostly functionally unisexual (or sometimes bisexual in RHAMNACEAE).

                                                      26 Petals connate at the base; stamens alternate to the petals and opposite to the sepals; fruit 4-8-locular, with 4-8 pyrenes

                                                      26 Petals separate (or absent in Rhamnus alnifolia); stamens opposite to the petals (when present) and alternate to the sepals; fruit 2-4-locular, with 2-4 pyrenes

                                                    25 Ovary 2-3- or 5-locular; fruit dry and dehiscent, a capsule; flowers bisexual (except Stillingia in EUPHORBIACEAE).

                                                        27 Ovary and capsule 5-locular; stamens 10-many.

                                                          28 Stamens 10; corolla urceolate, sympetalous

                                                          28 Stamens many; corolla spreading, apopetalous

                                                        27 Ovary and capsule 2-3-locular; stamens 2, 5, or 10.

                                                            29 Leaves < 3× as long as wide; stamens 5 or 10; ovary and capsule 2-3-locular; [plants collectively widespread].

                                                              30 Stamens 5; ovary and capsule 2-locular; leaves elliptic (widest near the middle), the teeth fine (usually > 5 points per cm of margin), and along much of the margin; inflorescence a terminal raceme; hairs of the lower leaf surface simple, erect

                                                              30 Stamens 10; ovary and capsule 3-locular; leaves obovate (widest towards the apex), the teeth obscure to coarse (usually < 4 points per cm of margin), and primarily in the upper half of the leaf; inflorescence a terminal or axillary raceme or cyme; hairs of the lower leaf surface either simple and appressed, or stellate.

                                                                 31 Leaf margins regularly and evenly serrate in the upper half of the leaf (usually nearly entire towards the base); inflorescence an elongate, many flowered (>30) raceme borne at the end of branchlets of the season; corolla of separate petals, the stamens separate; hairs of the lower leaf surface simple and appressed

                                                                 31 Leaf margins wavy or irregularly dentate, mainly in the upper half of the leaf; inflorescence a few flowered (<20) axillary raceme, cyme, or cluster; corolla fused basally into a tube, the stamens adnate to the tube; hairs of the lower leaf surface stellate