Kudzu
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- For the comic strip, see Kudzu (comic strip).
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| Pueraria lobata (Willd.) Ohwi |
Kudzu (クズ or 葛 Kuzu?), Pueraria lobata (syn. P. montana, P. thunbergiana), is one of about 20 species in the genus Pueraria in the pea family Fabaceae, subfamily Faboideae. It is native to southern Japan and southeast China in eastern Asia. The name comes from the Japanese word meaning vine. The other species of Pueraria occur in southeast Asia, further south.
Although edible for humans and livestock, kudzu is sometimes referred to as "the plant that ate the South," a reference to how kudzu's explosive growth has been most prolific in the southeastern United States due to nearly ideal growing conditions. Significant sums of money and effort are spent each growing season to prevent kudzu from taking over roads, bridges, power lines, and local vegetation.
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[edit] Description
Kudzu is a climbing, woody or semi-woody, perennial vine capable of reaching heights of 20–30 m (66-98 ft) in trees, but also scrambles extensively over lower vegetation. The leaves are deciduous, alternate and compound, with a petiole (leaf stem) 10–20 cm (4–8 in) long and three broad leaflets 14–18 cm (6–7 in) long and 10 cm (4 in) broad. The leaflets may be entire or deeply 2–3 lobed, and are pubescent underneath with hairy margins.
The flowers are borne in long panicles 10–25 cm (about 4–10 in) long with about 30–80 individual blooms at nodes on the stems (see image). Each flower is about 1–1.5 cm (about 0.4–0.6 in) long, purple, and highly fragrant. The flowers are copious nectar producers and are visited by many species of insects, including bees, butterflies and moths. Flowering occurs in late summer and is soon followed by production of brown, hairy, flattened seed pods, each of which contains three to ten hard seeds.
Once established, kudzu plants grow rapidly, extending as much as 20 m (60 ft) per season at a rate of about 30 cm (12 in) per day. This vigorous vine may extend 10–30 m (30–100 ft) in length, with basal stems 1–10 cm (1–4 in) in diameter. Kudzu roots are fleshy, with massive tap roots 10–20 cm (4–8 in) or more in diameter, 1–2 m (3–6 ft) or more in length, and weighing as much as 180 kg. As many as thirty stems may grow from a single root crown.
Kudzu grows well under a wide range of conditions and in most soil types. Preferred habitats are forest edges, abandoned fields, roadsides, and disturbed areas, where sunlight is abundant. Kudzu grows best where winters do not drop below –15 °C (5 °F), average summer temperatures are regularly above 27 °C (80 °F), and annual rainfall is 1000 mm (40 in) or more. In areas where winters drop below –15 °C, it will be killed to ground level, but the roots may send up new growth in the spring.
[edit] Uses
[edit] Culinary
The non-woody parts of the plant are edible. The young leaves can be used for salad or cooked as a leaf vegetable; the flowers battered and fried (like squash flowers); and the starchy tuberous roots can be prepared as any root vegetable.
The starchy roots are ground into a fine powder and used for varieties of Wagashi and herbal medicines. When added to water and heated, kudzu powder becomes clear and adds stickiness to the food. It is sometimes known as "Japanese arrowroot,", due to the similar culinary effect it produces.
The name Kudzu appeared first in Kojiki and Nihonshoki as a type of vine or Kazura (葛 or 蔓) used commonly by the people who lived in Kudzu (国栖), an area around present-day Yoshino, Nara prefecture. It is unclear whether the name was taken from the people or the name of the plant was applied to the people. Kudzu has been in use for over 1300 years and it is speculated that it goes back even further. Records from the Nara and Heian era indicate that kudzu was collected and sent as a part of tax. Even today, "Yoshino Kudzu" has the best image of kudzu powder yet. The Kagoshima prefecture is the largest producer of kudzu products.
[edit] Medicinal
Studies have shown that kudzu can reduce both hangovers and alcohol cravings.[1] [2]The mechanism for this is not yet established, but it may have to do with both alcohol metabolism and the reward circuits in the brain.
Kudzu also contains a number of useful isoflavones, including daidzein (an anti-inflammatory and antimicrobial agent), daidzin (a cancer preventive) and genistein (an antileukemic agent). Kudzu is a unique source of the isoflavone puerarin. Kudzu root compounds can affect neurotransmitters (including serotonin, GABA, and glutamate) and it has shown value in treating migraine and cluster headache [3].
In traditional Chinese medicine, where it is known as gé gēn (葛根), kudzu is considered one of the 50 fundamental herbs. It is used to treat tinnitus, vertigo, and Wei syndrome (superficial heat close to the surface).
[edit] Other uses
In the Southern United States, where the plant has been introduced to devastating consequences, kudzu is used to make soaps, lotions, and jelly, as well as feed for grazing animals. [4] [5]
[edit] Kudzu as an invasive exotic
Kudzu was introduced from Japan into the United States in 1876 at the Philadelphia Centennial Exposition, where it was promoted as a forage crop and an ornamental plant. From 1935 to the early 1950s the Soil Conservation Service encouraged farmers in the South to plant kudzu to reduce soil erosion, and the Civilian Conservation Corps planted it widely for many years. Kudzu was recognized as a pest weed by the United States Department of Agriculture in 1953, and was removed from its list of permissible cover plants.
Kudzu is now common throughout most of the southeastern United States, and has been found as far north as Pennsylvania, and as far south as Key West, Florida. It has also been found growing (rather inexplicably) in Clackamas County, Oregon in 2000 [6]. In all, kudzu infests 20,000 to 30,000 square kilometres of land in the United States and costs around $500 million annually in lost cropland and control costs. It cannot tolerate extremely low freezing temperatures that bring the frost line down through its entire root system; however it does require some cold weather (a solid frost or freeze annually).
Kudzu is also becoming a problem in northeastern Australia.
Kudzu vines can make walking across an area nearly impossible, as it takes over all horizontal and vertical surfaces, both natural and artificial. Its dense growth obstructs all views and movement into the area. It kills or degrades other plants by smothering them under a solid blanket of leaves, by girdling woody stems and tree trunks, and by breaking branches or uprooting entire trees and shrubs through its weight.
The spread of kudzu is mainly by vegetative expansion by runners and rhizomes and by vines that root at the nodes to form new plants. Kudzu will also spread by seeds, which are contained in pods and mature in the autumn. One or two viable seeds are produced per cluster of pods. These hard-coated seeds may not germinate for several years, which can result in the re-appearance of the species years after it was thought eradicated at a site.
[edit] Control
For successful long-term control of kudzu, the entire root system must be destroyed. If any root crowns remain, the plant will grow back. Mechanical methods involve cutting vines just below the ground then destroying all cut material. Close mowing every month or regular heavy grazing for two growing seasons, or repeated cultivation may be effective.
If done in the spring, cutting must be repeated as regrowth appears to exhaust the plant's stored carbohydrate reserves. Cut kudzu can be fed to livestock, burned or enclosed in plastic bags and sent to a landfill.
Late-season cutting should be followed up with immediate application of a systemic herbicide to the cut stems, to encourage transport of the herbicide into the root system. Repeated applications of several soil-active herbicides have been used effectively on large infestations in forestry situations.
Efforts are being organized by the U.S. Forest Service to search for biological control agents for kudzu, and a particular fungus is currently in testing.
The city of Chattanooga, Tennessee has undertaken a trial program using goats that graze on the plant. Currently the goats are grazing along the Missionary Ridge area in the east of the city [7].
[edit] References
- Part of this article was originally based on content from public domain web pages from the United States National Park Service and the United States Bureau of Land Management.
