Causonis japonica (also known by its synonym Cayratia japonica and common names bushkiller, yabu garashi and Japanese cayratia herb) is a vine plant in the grape family, Vitaceae. It is the type species of its genus and is native to tropical and subtropical Asia, Australia and the West Pacific.Plants of the World Online: Causonis japonica (Thunb.) Raf. (retrieved 26 December 2021) It is used as a traditional Chinese medicine to relieve swelling and heat, and to enhance diuresis and detoxification.
Description
Causonis japonica is a perennial herbaceous vine with compound, alternately branching leaves. Tendrils grow opposite each leaf. The leaves have 5 leaflets with dentate margins and a white coloration on the lower surface. The leaflets are arranged in a semi-palmate arrangement with 2 pairs of 2 with 1 singular leaflet with a longer stem in the center. It flowers in the late summer with red, white, and yellow flowers developing in umbels and producing grape-like berries with 2-4 seeds. In South Korea it flowers in July and August, with its fruit ripening in September and November, while in the southern hemisphere, in the Australian Northern Territory, it flowers and fruits in October.
This species may be confused with Virginia creeper in that they both have leaves with 5 toothed leaflets, but Virginia creeper lacks a petiolule (stem connecting a leaflet to the main leaf stem) on any of the leaflets.
Habitat It is a vine which grows on the edges of rainforests.
Taxonomy As can be seen from the list of synonyms, this species has been named and renamed many times.
It was first described as Vitis japonica in 1784 by Carl Peter Thunberg from a specimen found near Nagasaki.Thunberg, C.P. (1784), Flora Japonica: 104 Its current name was given in 1838 by Constantine Samuel Rafinesque, when he transferred the species to the genus Causonis.Rafinesque, C.S. (1838), Sylva Telluriana: 87
in 1798, Carl Ludwig Willdenow transferred it to the genus Cissus, to give Cissus japonica.Willdenow, C.L. (1798) in Species Plantarum Edn. 4, 1(2): 659 In 1918, Elmer Drew Merrill transferred it to the genus Columella. In 1911, François Gagnepain transferred it to the genus Cayratia, to give Cayratia japonica, a name which was accepted by Australian authorities until at least 2020,Brown, G.K. & Bostock, P.D. (December 2020), Appendix A: New names and name and status changes 2019 to 2020. Introduction to the Census of the Queensland Flora 2020: 19 and which remains its accepted name in South Korea.
As an introduced species in the US
Causonis japonica has been introduced in tropical areas of the United States including Texas, Louisiana, Mississippi, Alabama, and North Carolina, where it is known as bushkiller. It can outcompete native plants and stress native trees by blocking sunlight and weighing them down. Controlling this weed is difficult as it can regenerate from rhizomes that remain in the soil. Cutting the stems at the ground and applying a systemic herbicide will often kill the plant. Composting it is not recommended as it can re-sprout from buried stems.
References
External links
Causonia japonica: images & occurrence data from GBIF