Description: 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 2 or 3) at the end of a short shoot 2-4 cm long with 2-4 pairs of leaves; calyx tube forming a cup (hypanthium); pedicels, hypanthia and sepals covered in dense tomentum of short, woolly hairs and longer, straight hairs; sepals 4; petals 4, white, 1.2-2.2 cm long, 0.7-1.8 cm wide; corolla cruciform, 2.2-4.2 cm across; stamens about 55, filaments fused into bundles; style and hypanthium disk glabrous; each seed long-tailed. Flowers June to August. Similar Species: The hypanthium and sepals of Philadelphus microphyllus var. microphyllus are glabrous or only sparsely hairy at the base.