In Wisteria the wings remain adnate to the keel after anthesis (vs. separated from the keel in Wisteriopsis). The Asian species all have papillate callosities similar to those in Padbruggeafilipes but the North American W.frutescens has small ridge type callosities. The pods of all Asian species are gently torulose with a velutinous surface (striated, ridged, furrowed or tessellated in Padruggea and Austrocallerya). The North American W.frutescens has straight, smooth, glabrous pods.

Wisteriafrutescens (L.) Poir. ≡ Glycinefrutescens L.,

Robust, twining woody vines to more than 30 m in height. Stems green and pubescent when young, becoming grey or reddish brown at maturity, terete. Stipules 4–8 mm long, linear, sericeous, caducous. Stipels 3–4 mm long, filiform, sericeous, caducous. Leaves deciduous, chartaceous and villose when young, glabrous when mature, imparipinnate with (7 –)9–13(–15) leaflets, rachis 4–7 cm long, pubescent becoming glabrous. Leaflets 2–10 × 1–5 cm, ovate-elliptic or elliptic-lanceolate, upper surface glabrous (very finely pubescent in W.frutescens), lower surface with scattered hairs along veins, apex acute, acuminate or shortly caudate, margins entire or gently sinuate, base obtuse or cuneate. Inflorescence a terminal spreading to pendulous raceme 12–30(– 140) cm long, peduncle villose or pubescent. Flowers 15–30 mm long, emerging from April to May (June to August in W.frutescens). Floral bracts 5–15(– 23) mm long, brown or silvery chartaceous, linear or cupuliform, attenuate or caudate, caducous. Bracteoles 2–4 mm, (absent in W.frutescens) at top of pedicel, linear, acuminate, caducous. Pedicels 5–50 mm long, pubescent. Calyx 4–10 × 4–6 mm, campanulate or tubular, sparsely to densely pubescent or sericeous externally (sometimes with glandular hairs W.frutescens), five toothed, upper teeth acute, 3–5 mm long, lower teeth 3–6 mm long, (central tooth – 8 mm) acuminate, green or white. Standard 17–28 × 19–28 mm, suborbicular, lilac or pale purple, deflexed near the base (deflexed near the middle in W.frutescens), apex with a short mucro or retuse, nectar guide yellow, back of standard glabrous or sparsely pubescent along margin, callosities papillate either side of the midline at base (of ridge type in W.frutescens). Wing petals 12–20 × 5–8 mm, lilac or purple, equalling keel or slightly longer, glabrous, each semi-pandurate with basal claws 2–4 mm long (6–8 mm in W.brachybotrys). Keel petals 11–18 × 4–8 mm, lilac or purple, glabrous, united into a semi-pandurate cup, apex obtuse. Stamens diadelphous, nine fused together, the vexillary one free, all curved upwards at apex, glabrous. Ovary sericeous, style 3–5 mm long, curved upwards at apex, stigma punctate. Pods 10–24 × 1.2–3 cm, compressed, slightly torulose, (straight in W.frutescens) tardily dehiscent, exocarp smooth, surface densely velutinous, endocarp pithy, the seeds in shallow cavities, subseptate. Seeds (1 –)3–6(– 8), lenticular, (reniform-cuboid in W.frutescens) smooth, pale or dark brown, 8–10 × 8–12 × 2–4 mm, (8–10 × 4–6 × 4–6 mm in W.frutescens), hilum 1–2 × 1–3 mm, elliptic. Plate 3F–G.

China (Anhui, Fujian, Guangxi, Hebei, Henan, Hunan, Jiangsu, Jiangxi, Shaanxi, Shandong, Shangxi, Zhejiang); Japan; Korea; east North America.

In temperate forests from sea level to 1800 m, climbing among trees and shrubs.

The generic name commemorates the anatomist Professor Caspar Wistar (1761–1818), President of the American Philosphical Society. It also commemorates Caspar Wistar’s cousin Charles Jones Wister (1782–1865), friend of Thomas Nuttal who was the author of the name.