Trollius riederianus

Stems 1.1-4.5(-6) dm, base with persistent thatch of petioles from previous years. Leaves: basal leaves with petioles 5-20(-40) cm; cauline leaves 2-5, with broad, clasping, membranous sheaths. Flowers 3-6 cm diam.; sepals 5-7(-12), spreading, somewhat incurved, orange-yellow when fresh, obovate to ovate-orbiculate, 15-27 mm; petals 5-7, orange, ± length of stamens when pollen shed, 8-12 mm. Follicles 5-10, 7-10 mm including beak; beak straight.

Flowering summer. Moist meadows; 0-200 m; Alaska; Asia.

Trollius riederianus has been found in the flora only on the south side of Kiska Island in the western Aleutian Islands and at Cold Bay at the western end of the Alaska Peninsula; it is apparently native. The species is more widespread in eastern Asia, ranging from northern Japan and the coastal plain of China to the Russian Far East.