Stems decumbent, often rather long, somewhat woody and perennial at the base; pubescent above. Leaves pinnate, upper leaves three to five-foliate, nearly sessile, lower ones successively longer petioled, five to seven-foliate; leaflets oblong or oval, sharply toothed, blunt or pointed at the apex, narrowed at the base, 1 to 3 inches long; petioles sheathed at the base by large membranous stipules. Flowers conspicuous, three-fourths to 1 ¼ inches broad; calyx deeply five-lobed with five narrow bractlets, the calyx lobes ovate, acuminate, red or purple within, much exceeding the purple, ovate-lanceolate petals; pistils numerous, seated on an enlarged, pubescent receptacle which becomes spongy in fruit.
In swamps and peat bogs, Greenland and Labrador to New Jersey, Iowa, British Columbia, Wyoming, Alaska and California; also in northern Europe and Asia. Flowering from June to August.
Memoir 15 N. Y. State Museum
A. Purple Or Marsh Cinquefoil; Purplewort - Comarum palustre