1 Basal leaves lobed but not fully divided into 3 or more leaflets; stem leaves either unlobed and borne immediately below the flower (easily mistakable as a calyx) or lobed and borne well below the flower.

  2 Basal leaves lobed, and also toothed and variously cleft; stem leaves lobed and borne well below the flower; leaves not variegated

  2 Basal leaves lobed, the margins of the lobes entire; stem leaves unlobed and borne immediately below the flower (easily mistakable as a calyx); leaves often prominently variegated

1 Basal leaves compound, fully divided into 3 or more leaflets; stem leaves lobed and borne well below the flower.

    3 Stem branched, 4-11 dm tall, bearing 2 or more flowers; stem leaves petiolate; [subsection Virginianae].

      4 Heads of fruits cylindrical, >2× as long as diameter; fruit beaks 0.3-1.0 mm long; stem leaves (3-) 5-9 per whorl; peduncle naked above the stem leaves

      4 Heads of fruits ovoid to short-cylindric, <2× as long as diameter; fruit beaks 1.0-1.5 mm long; stem leaves 2-3 (-5) per whorl; peduncle with 2 additional subtending leaves.

        5 Base of stem leaves usually truncate to subtruncate, sometimes reniform or cordate, terminal leaflets deep green, margins proximally concave- to straight-sided, distally incised, thinly pubescent; anthers typically < 0.8-1.2 (-1.5) mm long; heads of achenes more or less ovoid-cylindric, 8-10 (-11) mm in diameter

        5 Base of stem leaves cordate or reniform, rarely subtruncate, terminal leaflets light green, margins proximally mostly straight- to convex-sided, variously lobed or serrate, variously pubescent; anthers typically > (0.9-) 1.1-1.5 (-1.7) mm long; heads of achenes ovoid to ovoid-cylindric, (9-) 10-12 (-14) mm in diameter

    3 Stem unbranched, 0.5-4 dm tall, bearing 1 flower; stem leaves sessile or petiolate.

          6 Sepals (5-) 8-20, cream-white, violet, blue, pink, or green; stem leaves sessile; [subsection Anemone; series Carolinianae].

             7 Stem densely pubescent above and below the stem leaves; stem leaves borne above the midpoint of the stem at anthesis; plant from a globose, vertically oriented bulb, lacking rhizomes; basal leaves 1-ternate, the 3 lobes sublobed or toothed, but not additionally divided; involucral leaves (1.5-) 3-6 cm long; achene bodies 2.7-3.5 mm long; achene beak sinuous, hidden in the achene indument

             7 Stem densely pubescent above the stem leaves, glabrous to very sparsely pubescent beneath the stem leaves; stem leaves borne at or below the midpoint of the stem at anthesis; plant with slender, horizontal rhizomes; basal leaves 1-3-ternate, the 3 primary lobes usually further divided into linear segments; involucral leaves 1-2.5 (-3) cm long; achene bodies 1.5-2.5 (-3.0) mm long; achene beak straight, extending out of the achene indument

          6 Sepals 5 (-8), white or bright yellow; stem leaves petiolate, the leaflets ovate, obovate, elliptic, lanceolate, or oblanceolate 2-8 cm long, 8-30 mm wide; [subsection Anemonanthea].

               8 Sepals bright yellow; [exotic]

               8 Sepals white; [natives, collectively widespread]

                 9 Ovaries and achenes with hairs 0.1-0.2 mm long; terminal leaflet broadest at or below the middle (lanceolate or ovate), serrate to below the middle; sepals 15 mm or more long

                 9 Ovaries and achenes with hairs 0.5-1.0 mm long; terminal leaflet broadest at or above the middle (elliptic, oblanceolate, or obovate), serrate only above the middle; sepals < 15 mm long.

                   10 Achene bodies 2.5-3.0 mm long; lateral leaflets of basal leaves toothed only (rarely lobed); terminal leaflet usually broadest at the middle; styles 0.5-1 mm long; sepals about 8 mm long

                   10 Achene bodies 3.0-4.5 mm long; lateral leaflets of basal leaves lobed or cleft (sometimes only toothed); terminal leaflet usually broadest above the middle; styles 1-2 mm long; sepals 6-15 mm long