Kudzu (), also called Japanese arrowroot or Chinese arrowroot, is a group of climbing, coiling, and trailing deciduous perennial vines native to much of East Asia, Southeast Asia, and some Pacific islands. It is invasive in many parts of the world, primarily North America. The vine densely climbs over other plants and trees and grows so rapidly that it smothers and kills them by blocking most of the sunlight and taking root space. The plants are in the genus Pueraria, in the pea family Fabaceae, subfamily Faboideae. The name is derived from the Japanese name for the plant East Asian arrowroot, (Pueraria montana var. lobata), kuzu (クズ/葛). Where these plants are naturalized, they can be invasive and are considered noxious weeds. The plant is edible, but often sprayed with herbicides.
Taxonomy
The name kudzu describes one or more species in the genus Pueraria that are closely related, and some of them are considered to be varieties rather than full species. The morphological differences between the subspecies of P. montana are subtle; they can breed with each other, and introduced kudzu populations in the United States apparently have ancestry from more than one of the subspecies. They are:
P. montana Pueraria montana var. chinensis (Ohwi) Sanjappa & Pradeep (= P. chinensis) Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep (= P. lobata) Pueraria montana var. thomsonii (Benth.) Wiersema ex D.B. Ward (= P. thomsonii) P. edulis P. phaseoloides – proposed to be moved to Neustanthus Various other species in Pueraria sensu stricto are also known as "kudzu" with an adjective, but they are not as widely cultivated or introduced.
Ecology Kudzu has been referred to as "quasi-wild" due to its long history of cultivation, selective breeding into various cultivars, and subsequent return to wild conditions. Some researchers suggest that humans are the main predator of kudzu in its native range, and that human use and cultivation of kudzu both contribute to its success as an invasive species and are a form of biological control for kudzu.
Propagation
Kudzu spreads by vegetative reproduction via stolons (runners) that root at the nodes to form new plants and by rhizomes. Kudzu also spreads by seeds, which are contained in pods and mature in the autumn, although this is rare. One or two viable seeds are produced per cluster of pods. The hard-coated seeds can remain viable for several years, and can successfully germinate only when soil is persistently soggy for 5–7 days, with temperatures above 20 °C (68 °F).
Once germinated, saplings must be kept in a well-drained medium that retains high moisture. During this stage of growth, kudzu must receive as much sunlight as possible. Kudzu saplings are sensitive to mechanical disturbance and are damaged by chemical fertilizers. They do not tolerate long periods of shade or high water tables. Kudzu is able to withstand environments ranging from sunny to shady upon reaching its mature stage; however, forest edges with greater light availability are optimal.
Invasive species
Kudzu's environmental and ecological damage results from its outcompeting other species for a resource. Kudzu competes with native flora for light, and acts to block their access to this vital resource by growing over them and shading them with its leaves. Native plants may then die as a result.When kudzu invades an ecosystem, it makes the leaf litter more labile, thereby lessening the carbon sequestration ability of the soil.
Americas
Kudzu is an infamous weed in the United States, where it can be found in 32 states. It is common along roadsides and other disturbed areas throughout most of the southeast, as far north as rural areas of Pulaski County, Illinois, and along the East Coast in sparser populations as north as the New York City Metropolitan Area and Boston, Massachusetts. The vine has become a sore point in Southern US culture. Estimates of its rate of spreading differ wildly; it has been described as spreading at the rate of 150,000 acres (610 km2) annually in 2009, although in 2015 the United States Forest Service estimated the rate to be only 2,500 acres (10 km2) per year.
A small patch of kudzu was discovered in 2009 in Leamington, Ontario, the second-warmest growing region of Canada after south coastal British Columbia. Kudzu was introduced from Japan into the United States at the Japanese pavilion in the 1876 Centennial Exposition in Philadelphia. It was also shown at the Chicago World's Fair. It remained a garden plant until the Dust Bowl era (1930s–1940s), when the vine was marketed as a way for farmers to stop soil erosion. The new Soil Conservation Service grew seventy million kudzu seedlings and paid $8 an acre (equivalent to $184 in 2025) to anyone who would sow the vine. Road and rail builders planted kudzu to stabilize steep slopes. Farmer and journalist Channing Cope, dubbed "kudzu kid" in a 1949 Time profile, popularised it in the South as a fix for eroded soils. He started the Kudzu Club of America, which, by 1943, had 20,000 members. The club aimed to plant 8 million acres (32,000 km2) across the South. Cultivation peaked at over one million acres (4,000 km2) by 1945. Once Soil Service payments ended, much of the kudzu was destroyed as farmers turned the land over to more profitable uses. The Soil Conservation Service stopped promoting kudzu altogether by the 1950s. Kudzu's ongoing mythos as a mile-a-minute invader is likely due to its visibility coating trees at wooded roadsides, thriving in the sunshine at the forest edge. Despite kudzu's notoriety, Asian privet and invasive roses have each proved to be greater threats in the United States.
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