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
basalasterid, not closely related to Jasminum (advanced asterids), and among the
eudicots quite distant from Citrus (advanced
rosids). An entirely misleading name for Philadelphus that is sometimes encountered is syringa;[3] this properly refers to the
lilacs, which are fairly close relatives of jasmine. The connection of the two shrubs lies in their introduction from
Ottoman gardens to European ones, effected at the same time by the Holy Roman emperor's ambassador to the
Sublime Porte,
Ogier Ghiselin de Busbecq, who returned to Vienna in 1562. The two shrubs appear together in
John Gerard's Herball, as "Blew Pipe" (the lilac) and "White Pipe Tree", for the woods of both are pithy and easily hollowed out.[4]
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 0.5-6 inches (1–14 cm) long. The
flowers are white, with four petals and sepals, 0.5-2 inches (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.
For a long time, Philadelphus coronarius was the only mock-orange of gardens, though some adventurous Americans grew the native P. inodorus that
Mark Catesby had discovered growing on the banks of the
Savannah River. It appeared in Lady Skipwith's garden lists and
George Washington ordered some from Bartram in 1792.[5] 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, selected for doubleness and large flowers, with some compromise as to scent.