This relative of the lemon is showing its discreet flowers in the Woodland Garden.
The genus Ptelea comprises only a handful of North American species, and belongs to the Rutaceae family, which also includes the citrus fruits. All members of the family have aromatic foliage. P. trifoliata is a small tree growing to no more than 7 m in height. As the specific name trifoliata indicates, the leaves comprise three slender leaflets, with the central one being symmetrical and the two outer leaflets being asymmetrical. If held up to the light the leaf blade can be seen to be covered in oil glands, from which the leaf scent is released. Corymbs of unisexual green-white, star-shaped flowers are carried on downy stalks, and the male flowers are soon shed from the corymb. The fruits are rounded and flattened, and these have earned this species the common name of hop tree. Occurring in the eastern and northern United States, P. trifoliata was introduced to English gardens in the early 1700’s.