Mock-orange (Philadelphus, pronounced /ˌfɪləˈdɛlfəs/) is a genus of about 60 species of shrubs from 1 to 6 m tall, native to North America, Central America, Asia and (locally) in southeast Europe.
They are named "mock-orange" in reference to their flowers, which in wild species look somewhat similar to those of oranges and lemons (Citrus) at first glance, and smell of orange flowers and jasmine (Jasminum). But Philadelphus is a basal asterid, not closely related to Jasminum (advanced asterids), and among the eudicots quite distant indeed from Citrus (advanced rosids). An entirely misleading name for Philadelphus that is sometimes encountered is syringa; this properly refers to the lilacs, which are fairly close relatives of jasmine.
Most are deciduous but a few species from the south of the genus' range are evergreen. The leaves are opposite, simple, with serrated margins, from 1 to 14 cm long. The flowers are white, with four petals and sepals, 1-4 cm diameter, and commonly (but not in all species) sweetly scented. The fruit is a small capsule, containing numerous small seeds. The bark is thin and flaky, finely shredding in longitudinal strips.
Mock-oranges are used as food plants by the larvae of some Lepidoptera species including The Engrailed (Ectropis crepuscularia). A noted pathogen of the Sweet Mock-orange (P. coronarius) is the undescribed proteobacterium called "Pseudomonas tomato" (pv. philadelphi).
Mock-oranges are popular shrubs in parks and gardens, grown for their reliable display of late spring flowers; the scented species are particularly valued. In addition to the species, there are numerous garden origin hybrids and cultivars available.
Lewis' Mock-orange (P. lewisii) is the state flower of Idaho