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1 Plant an herb, shrub, or tree (if a partially scandent shrub, then the stems also with conspicuous recurvedprickles as in Eleutherococcus trifoliatus); leaves simple or compound.
2 Leaves simple, peltate or cordate, roundish (if lobed, with 3-5 rounded lobes), 0.3-10 cm wide; rhizomatous, creeping herbs; [subfamily Hydrocotyloideae]
6 Leaves 2-3× compound, at least the final order of division pinnate; leaves either 1 from a subterranean stem or 2-many, alternate on an aboveground stem; inflorescence compound, consisting of (2-) 3-many umbels, either on a separate peduncle from the rhizome or in a terminal panicle or raceme of umbels; fruit purple or black; [subfamily Aralioideae; tribe Aralieae]
6 Leaves 1× palmately compound, leaflets 3-7; leaves 3-5 in a whorl at the summit of the stem (Panax) or many, clustered on spur shoots (Eleutherococcus); inflorescence of a single, simple umbel borne terminally on the stem; fruit red to yellow (Panax), purple or black (Eleutherococcus) or orange (Heptapleurum).
7 Plant non-native shrubs or trees (sometimes partially epiphytic or scandent); with or without stem prickles; fruit black, dark purple, or orange; [subfamily Aralioideae; tribe Schefflereae].
8 Plant a shrub (to 7 m tall), with prominent stem prickles; fruit black or dark purple when ripened; leaves either trifoliate (E. trifoliatus) or palmately compound and 5-foliolate (predominantly so in E. sieboldianus)
8 Plant a shrub (to 4 m tall in H. arboricola) or tree (to 12 m tall in H. actinophyllum), lacking stem prickles; fruit orange when ripened; leaves palmately compound, usually 7-9-foliolate (occasionally with 5 or 10 leaflets, if 5, this not predominant across the plant)
9Leaflets (3-) 5, petiolulate, the petiolules (7-) 10-25 mm long; larger leaflets 6-15 cm long, 3.5-7 cm wide, averaging about 1.8× as long as wide, the apexacuminate; fruit bright red when ripe, smoothly elliptical in ×-section; petals light green; inflorescence erect in bud; underground storage organ an elongate root, this vertical or horizontal, and sometimes branched
2 Leaf bladesoval in shape, ca. 1.5-2× as long as wide, at maturity floating on the water’s surface; underwater portions of fresh plant coated in transparent mucilage
2 Leaf bladesorbicular in shape, ca. 1× as long as wide, at maturity floating on the water’s surface, emersed, or submersed; underwater portions of fresh plant not mucilaginous (though possibly with green algae, etc.).
3 Leaves small, < 8 cm in diameter, at maturity emersed or submersed
12Perianth parts numerous (usually showing differentiation into sepals and petals, though often with some intergradation), borne in a spiral; stamens numerous; leaves usually > 10 cm long or > 10 cm wide, or both (a few northern species of Nymphaea with leaves as small as 2.5 cm × 2.5 cm); [Basal Angiosperms]
12Perianth parts 3-6 (either differentiated or not into sepals and petals); stamens either 3, or 9-12 (-18), or >20; leaves 1-10 cm long, 1-10 cm wide; [Monocots].
14 Flowers unisexual, white, the sepals and petals separate; stamens 3, 6, 9, 12, 15, or 18; leaves either with a central area of spongiformcells (most easily seen on the lower leaf surface) (Limnobium), or without spongiformcells (Ottelia)
1Inflorescence, flower, and fruit structure various, but not with the combination of features as above (sometimes the flowers in a head subtended by bracts, e.g. Eryngium in APIACEAE, but then with other features differing, such as stamens 4, or green calyx present, or petals separate, or fruit a schizocarp of mericarps, etc.).
3Basal leaves 2-lobed, hinged between the lobes, each lobe with stiff, marginal, eyelash-like bristles; [Coastal Plain of NC and SC, rarely planted and weakly naturalized elsewhere]
26 Flowers radially symmetrical; inflorescence either of a solitary flower or of a 1-7-flowered terminal cyme; petals 5, 8-12, or 0; sepals 5 (green), 3 (brown), or 5-9 (yellow); stamens 5, 12, or many.
27Gynoecium either of a single pistil with 6 carpels or of a single pistil with 4 carpels or of 2 nearly separate carpels; fruit a simple capsule (or deeply 2-lobed); flowers white, brown, or greenish, either of 5 fused or distinct white petals and 5 fused or distinct green sepals, or of 3 fused brown or greenish petaloidsepals.
32 Flowers typically with 2 or 4 (-5) white-colored tepals; leaf bases conspicuously oblique (sometimes variegated); fruit unequally or subequally 3-wingedcapsules; [ornamental waifs or uncommon non-natives]
40 Leaves tubular, with a sutured ventralflange, erect or reclining, adapted as a pitfall for insects (flat, phyllodial leaves sometimes present as well, common in the winter in some species, such as S. oreophila)
41 Stem leaves opposite; perianth 5-merous, at least the corolla bilaterally symmetrical (barely so in VALERIANACEAE), or the parts curved so as to be asymmetrical (Pedicularis in OROBANCHACEAE); stamens 2, 3, or 4.
43Corolla distinctly 2-lipped (with prominently large upper and lower corolla lobes) or hooded (the upper liphood-like), distinctly bilaterally symmetrical, or the lobes twisted so as to make the corolla asymmetrical.
44Corolla yellow, the upper lip often slightly to strongly maroon, hooded but the corolla lobes twisted so as to make the flower asymmetrical
66 Leaves serrate or crenate; stamens 10; [plants of various habitats, especially rock outcrops and bottomland forests and streambanks, never in tidal marshes]
1Inflorescence, flower, and fruit structure various, but not with the combination of features as above (sometimes the flowers in a head, e.g. Eryngium in APIACEAE, but then with other features differing, such as stamens 4, or green calyx present, or fruit a schizocarp of mericarps, etc.).
2 Plant an herb, sometimes sprawling, reclining (e.g. Cymbalaria in PLANTAGINACEAE, Aconitum in RANUNCULACEAE), but lacking climbing adaptations such as tendrils or twining stems.
2 Leaves “normal” (non-septate, flat, continuous, and in some cases lobed, toothed, or spinose-margined); flowers blue, yellow, white, or whitish-green; [plants of wetlands or uplands].
7 Stem leaves palmately 3-5-foliolate with linearleaflets, differing from the simple basal leaves; corollas white; [native, of blackland prairies and associated disturbed areas, from AL and TN westward]
11 Leaves cordate or truncate at the base; flowers white, green, yellow, blue, or purple;
13 Flowers greenish or blue; leaves all simple (sometimes stem leaves lobed); inflorescence a head or very congested (subcapitate) umbel; [plants of wetland situations, prostrate, creeping, or erect].