Philadelphus zeyheri Schrad. Ex DC.

A deciduous shrub of very vigorous spreading habit up to 8 ft high, considerably more in width; bark deep brown, slightly peeling; young shoots glabrous. Leaves broadly ovate to lanceolate, tapered at the base, slender-pointed, varying from coarsely toothed to nearly entire, 21⁄2 to 4 in. long, 3⁄4 to 2 in. wide, glabrous above, downy beneath along each side of the midrib and chief veins, with occasional hairs between. Flowers pure white, 11⁄2 to 13⁄4 in. across, produced during June in a terminal corymb of three to seven blossoms (sometimes solitary). Petals oval; style distinctly longer than the stamens; calyx glabrous, with slender lobes 1⁄2 in. long.

This philadelphus, of unrecorded origin, was in cultivation early in the 19th century and reputed to have come from N. America. It was compared by de Candolle to P. coronarius, differing in its leaves being rounded at the base and in its fewer, larger and scentless flowers. It is treated by Dr Hu as a variety of P. coronarius, but some authorities consider it to be a hybrid between that species and P. inodorus var. grandiflorus.

It is very distinct in its comparatively low, spreading habit, but its flowers are scentless, it blossoms poorly and is of inferior quality. The young shoots are apt to be killed back in winter, which may be due to their sappy vigour.