Wisteria

Wisteria is a genus of flowering plants in the legume family, Fabaceae (Leguminosae). The genus includes four species of woody twining vines that are native to China, Japan, Korea, Vietnam, southern Canada, the Eastern United States, and north of Iran. They were later introduced to England, France, Germany and various other countries in Europe. Some species are popular ornamental plants. The genus name is also used as the English name, and may then be spelt 'wistaria'. In some countries in Western and Central Europe, Wisteria is also known by a variant spelling of the genus in which species were formerly placed, Glycine. Examples include the French glycines, the German Glyzinie, and the Polish glicynia.

Description

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. 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. 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. 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. The flowers are fragrant, and especially cultivars of W. brachybotrys, W. floribunda, and W. sinensis are noted for their sweet and musky scents. 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. The seeds are produced in pods similar to those of Laburnum.

Taxonomy

The genus Wisteria was established by Thomas Nuttall in 1818. He based the genus on Wisteria frutescens, previously included in the genus Glycine. Nuttall stated that he named the genus in memory of the American physician and anatomist Caspar Wistar (1761–1818). Both men were living in Philadelphia at the time, where Wistar was a professor in the School of Medicine at the University of Pennsylvania. Questioned about the spelling later, Nuttall said it was for "euphony", but his biographer speculated that it may have something to do with Nuttall's friend Charles Jones Wister Sr., of Grumblethorpe, the grandson of the merchant John Wister. Various sources assert that the naming occurred in Philadelphia. It has been suggested that the Portuguese botanist and geologist José Francisco Corrêa da Serra, who lived in Philadelphia beginning in 1812, four years before his appointment as ambassador of Portugal to the United States, and a friend of Wistar, proposed the name "Wistaria" in his obituary of Wistar.

As the spelling is apparently deliberate, there is no justification for changing the genus name under the International Code of Nomenclature for algae, fungi, and plants.

Classification The genus was previously placed in the tribe Millettieae. Molecular phylogenetic studies from 2000 onwards showed that Wisteria, along with other genera such as Callerya and Afgekia, were related and quite distinct from other members of the Millettieae. A more detailed study in 2019 reached the same conclusion, and moved Wisteria to the expanded tribe Wisterieae.

Species

As of September 2023, Plants of the World Online accepted four species:

Fossil species Additionally, the following fossil species have been described:

†Wisteria fallax (Nath.) Tanai, Onoe †Wisteria kamtschatica Cheleb. †Wisteria ligniata Miki. †Wisteria shanwangensis Wang, Dilcher,. Zhu, Zhou et Lott †Wisteria sichote-alinensis Akhmet. †Wisteria taoiana Wang, Dilcher,. Zhu, Zhou et Lott

Ecology Wisteria species are used as food by the larvae of some Lepidoptera species, including different kinds of moths.

Toxicity All parts of the plant contain a saponin called wisterin, which is toxic if ingested, and may cause dizziness, confusion, speech problems, nausea, vomiting, stomach pains, diarrhea and collapse. There is debate over whether the concentration outside of the seeds is sufficient to cause poisoning. Some Japanese sources assure that parts of the W. floribunda can be eaten at certain stages if prepared properly and in moderate amounts: young shoots and leaves may be eaten after blanching or boiling before serving with rice or fried while seeds may be consumable if harvested between July to September when they are not bitter. Nevertheless, wisteria seeds outside that caveat have caused cases of poisoning in children and pets of many countries, producing mild to severe gastroenteritis and other effects.

Cultivation

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