Philadelphus is a genus of shrubs; twigs without stipules; bark mostly shredding or flaking.
Leaves opposite, simple, margins entire to toothed ours are all deciduous with no notable fall color.
Flowers white, all but P. inodorus are sweet smelling; 4-parted, stamens numerous, ovary inferior, 4-parted.
Fruit a dry capsule with numerous small seeds, opening along the center of each of the 4 parts (loculicidal).
Notes: Widely cultivated and hybridized, often with numerous petals replacing stamens (as in cultivated roses).