Philadelphus argyrocalyx (Silvercup Philadelphus)
Erect shrub 1-2 m tall; leaves opposite, ovate, ovate-lanceolate or narrowly elliptic, margins entire, 10-35 mm long, 4-17 mm wide, glabrous or glabrescent above, sparsely villous hairy below, petiole about 2 mm long; flowers usually solitary (rarely...