P. multiflorum.: stem round, 2 feet high, arching; leaves alternate, ovate-oblong; flowers axillary, on short branched one- or many-flowered peduncles, drooping, white with greenish tips; filaments hairy. - Woods and thickets. Fl. May, June.

P. officinale: stem angular, 1 foot high; leaves alternate, ovate-oblong; flowers axillary, on short one- or two-flowered peduncles; filaments smooth. - Mountain woods. Fl. May, June.