Wisteria frutescens

Wisteria frutescens (American Wisteria) is a woody, deciduous, perennial climbing vine of the Fabaceae family. It is native to the wet forests and stream banks of the southeastern United States, with a range stretching from the states of Virginia to Texas (Northeast Texas Piney Woods) and extending southeast through Florida.

American Wisteria can grow up to 15m long over many supports via powerful clockwise-twining stems. It produces dense clusters of blue-purple, two-lipped, 2-cm-wide flowers on racemes 5–15 cm long in late spring to early summer. These are the smallest racemes produced by any member of the Wisteria family. Though it has never been favored in many gardens for this characteristic, many bonsai artists employ American Wisteria for its manageably-sized flowers.

The foliage consists of shiny, dark-green, pinnately compound leaves 10–30 cm in length. The leaves bear 9-15 oblong leaflets that are each 2–6 cm long. It also bears numerous poisonous, brown, bean-like seed pods 5–10 cm long that mature in summer and persist until winter. American Wisteria prefers moist soils. It is considered shade tolerant, but will flower only when exposed to partial or full sun. It grows best in USDA plant hardiness zones 5-9.

Several characteristics distinguish American Wisteria from its Asian counterparts. It grows only two-thirds as tall, its racemes are half as long (the shortest of the Wisteria family), and its bloom time is sometimes shorter than many Asian varieties. Its flowers are not scented, and its seed pods are smooth rather than velvety. Its most redeeming feature is the fact that it is much less invasive than its Asian counterparts, especially the beautiful but ruthless Chinese Wisteria (Wisteria sinensis).

American Wisteria is very similar to Kentucky Wisteria (Wisteria macrostachya) which has been considered a variety of W. frutescens but grows somewhat differently and has a fragrance.