Philadelphus gordonianus

From Gardening Wiki

PHILADELPHUS GORDONIANUS, also called Gordon's Syringa.

Philadelphus gordonianus or mock orange gordonianus.

A fine shrub, with flowers similar to the preceding, but later in period of bloom and scentless. Grows to 12 ft. and is especially adapted to the border where tall spreading plants are desired. Practically immune from insect pests, and, like the other varieties, named, is a strong, vigorous grower and thrives in partial shade as well as in sunny locations.