Fabaceae (Leguminosae), the Pea Family
This is an extremely fast-growing, climbing and trailing perennial vine. Plants develop an extensive and deep root system, and over time, produce massive tubers that can weigh as much as 400 pounds. The stems are herbaceous and hairy when young, becoming fibrous to woody with age, and can grow to 100 feet long. The leaves are alternately arranged, trifoliate (with three leaflets) and borne on long petioles. The lateral leaflets are typically two-lobed and the terminal leaflet three-lobed, although sometimes the leaflets are unlobed. Both the upper and lower surfaces of the leaflets bear appressed golden hairs. The pink to reddish-purple flowers, produced mostly in the summer and autumn months in Florida, are arranged in clusters of two to three on elongated racemes in the upper leaf axils. The flowers, which measure 0.5 inch across, have the classic pea form, with an enlarged upper banner petal and two lower petals united to form a keel. The flowers have a sweet fragrance reminiscent of grape candy or jelly. The 3-to 4-inch-long flat pods, with bulges over the seeds, are brown at maturity and covered with golden hairs. Each pod contains from three to 10 seeds, which are reddish-brown in color with a white hilum (attachment scar).
Kudzu is native to eastern and southeastern Asia and the western South Pacific islands. It has become naturalized in central Asia, eastern Europe, southern Africa, much of the eastern and central United States and parts of the West Indies and Central America. Kudzu grows best in full sun and often climbs high up into trees, forming dense masses of vegetation along roadsides, watercourses and forest edges.
This species has escaped from cultivation and occurs in disturbed habitats and hammock edges throughout the state. Herbarium specimens document kudzu scattered from Escambia County on the western panhandle to Miami-Dade County on the southern peninsula.
The cultivated hyacinth bean (Lablab purpureus) and native, trifoliate legumes such as ticktrefoils (Desmodium spp.) may bear superficial resemblance to kudzu but lack its massive stature; large, lobed leaflets covered in golden hairs; and grape-scented flowers.
Adventitious roots develop at stem nodes that contact the soil surface, eventually forming a root crown from which another plant will sprout. The seed is dispersed by birds, mammals and water but has a very hard outer coat that requires scarification or burning to germinate. Seeds may accumulate in the soil for years and then germinate en masse when an infestation is burned. Both seeds and stem fragments may be spread in contaminated soil.
In East Asia, kudzu has a long history of use for food, medicine, fiber and forage. It was introduced from Japan to the United States as an ornamental at the Philadelphia Centennial Exposition in 1876. In the early 20th century, kudzu was promoted in the southeastern United States as an inexpensive livestock forage, and starting in 1933, the United States Soil Conservation Service distributed kudzu seedlings as part of its efforts to control agricultural erosion. By the 1950s, kudzu's aggressive, weedy tendencies were becoming more widely known, and its use was discouraged. It is now listed as a noxious or restricted plant in 13 states. Kudzu forms large impenetrable masses that engulf and smother trees and understory vegetation. Its large tuberous roots allow it to withstand drought, freezing temperatures and periodic burning and make control particularly challenging.
http://www.se-eppc.org/manual/kudzu.html (accessed January 30, 2012)