Wisterias climb by twining their stems around any available support. W. floribunda (Japanese wisteria) twines clockwise when viewed from above, while W. sinensis (Chinese wisteria) twines counterclockwise. This is an aid in identifying the two most common species of wisteria.[4] They can climb as high as 20 m (66 ft) above the ground and spread out 10 m (33 ft) laterally. The world's largest known wisteria is the Sierra Madre Wisteria in Sierra Madre, California, measuring more than 1 acre (0.40 ha) in size and weighing 250 tons. Planted in 1894, it is of the 'Chinese lavender' variety.[5]
The leaves are alternate, 15 to 35 cm long, pinnate, with 9 to 19 leaflets.
The flowers have drooping racemes that vary in length from species to species. W. frutescens (American wisteria) has the shortest racemes, 5–7 centimetres (2.0–2.8 in). W. floribunda (Japanese wisteria) has the longest racemes, 90 centimetres (35 in) in some varieties and 120 centimetres (47 in) or 200 centimetres (79 in) in some cultivars.[6][7][8] The flowers come in a variety of colors, including white, lilac, purple, and pink, and some W. brachybotrys (Silky wisteria) and W. floribunda cultivars have particularly remarkable colors.[9][7] The flowers are fragrant, and especially cultivars of W. brachybotrys, W. floribunda, and W. sinensis are noted for their sweet and musky scents.[10][7] Flowering is in spring (just before or as the leaves open) in some Asian species, and in mid to late summer in the American species.