Herbs , perennial, from short, slender rhizomes. Leaves basal and cauline, simple, proximal leaves petiolate, distal leaves sessile; cauline leaves alternate. Leaf blade palmately 5-11-lobed; segments broadly cuneate, margins lacerate to serrate. Inflorescences terminal, ±many-flowered corymbs, 2.5-43 cm; bracts inconspicuous, linear-lanceolate, not forming involucre. Flowers bisexual, radially symmetric; sepals not persistent in fruit, 3-5(-7), greenish white, concave-cupped, broadly ovate to obovate, clawed, 3-6 mm; petals absent; stamens ca. 50-100; outer filaments 15-20, spatulate, often distally wider than anthers, inner filaments not dilated; staminodes absent between stamens and pistils; pistils ca. 15, simple; ovule 1 per pistil; style present. Fruits utricles, aggregate, sessile, ellipsoid to obovoid, 4-angled in cross section, sides prominently veined; beak terminal, curved to hooked, 0.4-0.8 mm. x =8.
Sep 4 or 5, broadly obovate, caducous; pet and staminodes none; stamens very numerous, the filaments widened distally and often wider than the short, oblong anthers; pistils several, small; styles short, subulate; fr a 4- nerved, thin-walled, 1-seeded, dehiscent utricle; stout perennials with large, alternate, palmately divided lvs and broadly rounded, corymbiform clusters of small white fls. Monospecific.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
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