Aerial shoots 30-100(-110) cm, from caudices, rarely with ascending rhizomes, caudices ascending to vertical. Basal leaves 1-5, ternate; petiole 5-35 cm; terminal leaflet sessile or nearly so, oblanceolate to obovate, 2-9(-12) × 2-5(-7) cm, base cuneate to broadly cuneate, margins coarsely serrate and incised on distal 1/2, apex acuminate to narrowly acute, surfaces pilose, more so abaxially; lateral leaflets usually 1-2×-lobed or-parted, occasionally unlobed; ultimate lobes 10-30(-40) mm wide. Inflorescences (1-)3-9-flowered cymes; peduncle villous; primary involucral bracts 3(-5), secondary involucral bracts 2(-3), (1-)2-tiered, ternate, ±similar to basal leaves, bases distinct; terminal leaflet ±sessile, elliptic to oblanceolate, 2-10(-12) cm (2 cm in secondary involucre) × 2-5(-7) cm, bases cuneate, margins coarsely serrate and incised on distal 1/2, apex acuminate to narrowly acute, surfaces pilose, more so abaxially; lateral leaflets unlobed or 1×-lobed or-parted; ultimate lobes 8-25(-35)mm wide. Flowers: sepals usually 5, green, yellow, or red (rarely white or abaxially green to green-yellow and adaxially green or yellow and tinged red), oblong, ovate, or obovate, 6.5-20 × 2.5-10mm, abaxially hairy, adaxially glabrous or nearly so; stamens 50-70. Heads of achenes oblong-ellipsoid, rarely obconic; pedicel 13-25(-30) cm. Achenes: body obovoid, 2-3.7 × 1.5-2mm, not winged, densely woolly; beak curved, 1-1.5mm, puberulous, not plumose.
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Much like A. cylindrica, averaging coarser and more loosely hairy; primary lf-segments rhombic-ovate, with the margins toothed or incised to below the middle and ± convex toward the base; involucral lvs 3; peduncles mostly 1–3, some of them often with a 2-lvd secondary involucre; sep greenish-white or less often pure white; seldom red, 7–13(16) mm; fruiting head ovoid, 1.5–3 cm; achenes densely woolly; style 1–1.5 mm, short-hairy, often ± spreading; 2n=16. Dry or open woods; e. Que. to N.D., s. to Ga., Ala., and Ark. June–Aug. Some plants from the n. part of the range diverge toward A. cylindrica in their somewhat narrower heads and in having the lf-segments more cuneate below. These have been segregated as var. alba A. W. Wood or A. riparia Fernald, but they do not appear to be sharply separable from A. virginiana.
Dry open woods. Dry, rocky, open woods, thickets and river banks; at elevations from sea level to 2,000 metres.
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