Herbs, perennial, from short caudices. Leaves basal and cauline, proximal leaves petiolate, distal leaves sessile or nearly so; cauline leaves alternate. Leaf blade deeply palmately divided into (3-)5-7 segments, segments obovate, ± 3-lobed, margins coarsely toothed, often incised. Inflorescences terminal, 1-3[-7]-flowered open cymes or flowers solitary; peduncle 2-30 cm; bracts leaflike, not forming involucre. Flowers bisexual, radially symmetric; sepals not persistent in fruit, (4-)5-9[-30], white to orange-yellow [orange-red or purplish], ± plane [strongly concave and incurved], elliptic, orbiculate, or obovate, sometimes short-clawed, 10-30 mm; petals 5-25, distinct, yellow or orange, plane with cupped base of blade, linear-oblong [ovate], ± clawed, 2-10[-40] mm; nectary within pocketlike base of blade; stamens 20-75; filaments filiform; staminodes absent between stamens and pistils; pistils 5-28[-50], simple; ovules 4-5(-9) per pistil; style present. Fruits follicles, aggregate, sessile, oblong, sides transversely veined; beak terminal, straight, 2-4 mm. Seeds black or dark brown, faceted to angular, dull or lustrous. x=8.
North temperate and arctic regions, North America, Europe, Asia.
Species ca. 30 (3 in the flora).
As many as 10 Eurasian species of Trollius have been cultivated in North America as ornamentals. Of these, only T. europaeus Linnaeus has been reported to escape. The species infrequently persists near old dwellings in New Brunswick (B.Boivin 1966; H.Hinds, pers. comm.). Trollius europaeus may be distinguished from all North American species by its globose flowers with strongly incurved sepals (in North American species flowers are shallowly bowl-shaped with sepals ± spreading).
|1||Petals 5–7, ± length of stamens when pollen shed, 8–12 mm; Alaska.||Trollius riederianus|
|1||Petals 10–25, 1/2–2/3 length of stamens when pollen shed, 3–6 mm; Washington to Rocky Mountains, and e United States.||> 2|
|2||Sepals white when fresh; plants of various moist habitats (often ± acidic), w North America.||Trollius albiflorus|
|2||Sepals yellow when fresh; plants restricted to alkaline meadows and swamps (fens), e United States.||Trollius laxus|