Stems slender, smooth or finely hairy above, 1 to 5 feet high, usually several or many plants together and spreading by underground rootstocks. Leaves thin, triple-nerved, linear-lanceolate, 2 to 5 inches long, entire or toothed with somewhat appressed teeth, long pointed at the apex, sessile or the lowest leaves petioled. Heads of flowers very small, about one-eighth of an inch or less high, arranged on one side of spreading branches which form a large, often loose panicle; rays four to six in number, short; bracts of the involucre thin, linear and pointed.
Hillsides and thickets or banks of streams, Newfoundland to Saskatchewan, south to Virginia, Tennessee and South Dakota. Flowering from August to October.
Memoir 15 N. Y. State Museum