This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol2", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Fleshy perennial herbs, with erect, mostly simple stems, broad, rather thin dentate or entire leaves and dioecious or polygamous, yellow, greenish or purplish flowers in terminal cymes. Flowers 4-parted or 5-parted. Calyx shorter than the petals. Carpels distinct, erect. Style very short or none. [Greek, rose, referring to the rose-scented roots.]
Rhodiola rosea L. Sp. Pl. 1035. 1753.
Sedum roseum Scop. Fl. Cam. Ed. 2, 326. 1772.
Sedum Rhodiola DC. Plantes Gras. pl. 143. 1805.
Perennial, branched at the base, or simple, erect or ascending, glabrous and somewhat glaucous, 4'-12' high. Leaves sessile, oval or slightly obovate, acute or obtuse at the apex, narrowed or rounded at the base, dentate or entire, 6"-12" long. 3"-5" wide, the lower ones smaller; cyme terminal, dense, •-2' broad; flowers dioecious, yellowish-green or purplish, 2 1/2"-4" broad; sepals oblong, narrower and shorter than the petals; staminate flowers with 8 (rarely 10) stamens, the pistillate ones with 4 (rarely 5) carpels; follicles purple, about 2" long, only their tips spreading.
In rocky places, Labrador and arctic America to Maine and Vermont; Chittenango Falls, New York; cliffs on the Delaware River in eastern Pennsylvania. Northern and alpine Europe and Asia. Root rose-scented. Snowdon rose. May-July.