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..
Anemone trifolia L. Sp. Pl. 540. 1753.
Stout, 6'-16' tall, nearly glabrous throughout. Basal leaves mostly 3-divided (sometimes 4-5-divided), long-petioled, dentate, often somewhat lobed; involucral leaves stout-petioled, 3-parted, the divisions oblong-lanceolate, acute or acuminate at the apex, dentate, often slightly lobed, 1'-3' long; flower solitary, white, l'-l 1/2' broad when expanded; peduncles 1'-4' long; sepals oblong to oval; head of fruit globose, s"-6" in diameter; achenes 10-20, oblong, finely pubescent, tipped with the hooked style.
Southern Pennsylvania, southwestern Virginia, North Carolina and Georgia, chiefly in the mountains; in Virginia usually in company with the lily-of-the-valley. Also in the south Austrian Alps and the mountains of northern Italy. May.