A perennial, semi-woody, nonnative vine with invasive, uncontrollable, smothering growth. Its many rampantly growing, hairy vines trail, sprawl, and loosely twine from a large, central root crown. The stems can be an inch or more in diameter in southern states. New growth is soft-hairy.
The roots are large, swollen tubers that can descend more than 13 feet into sandy loam soils.
The flowers are pea-like, grape scented, purple, to ¾ inch wide, and grow in elongated clusters. Flowering is in late July to September (in full sun).
The leaves are alternate, compound, with 3 dark green leaflets that are 2¾–10 inches long, with or without irregular, shallow lobes; hairy beneath.
The fruits are elongated, beanlike, hairy pods growing in clusters. Few of the seeds are viable, but the vines take root where they touch the ground, creating new plants.
Similar species: The native hogpeanut (Amphicarpaea bracteata) can look similar, but its leaves do not exceed the size of a human hand, and the small hairs on the stems are pressed against the stem and are white.
Length: vine stems to 100 feet; entire acres can be covered.
Found locally in Jackson, St. Louis, Howard, Christian, Wayne, Reynolds, Douglas, Newton, Lawrence, Ralls, and Taney counties. Patches have also been sighted along the route of Old US Highway 66 in Phelps Co. and along US Highway 67 in Madison and St. Francois counties.
Habitat and Conservation
A nonnative invasive plant that prefers well-drained, sandy loams and full sun (though it will grow in shade). It tolerates drought but cannot endure wet soils. In Missouri, the aboveground growth dies back to the crowns each winter. Potentially may be found statewide. Now present in at least 10 southern Missouri counties, plus Howard, Jackson, Ralls, and St. Louis counties. Originally planted in Missouri for bank stabilization, before its invasive nature was understood.
Invasive. This nonnative vine grows up to one foot per day in early summer and can cover everything in its path. In the South, it has become destructive to the point of pulling down power poles, breaking power lines, collapsing buildings, and killing trees. Under good growing conditions, kudzu can become an impenetrable mass of vines. Sugars produced in the leaves are transferred to the roots as starch, which is stored in swollen taproots that are as impressive as the aboveground vines.
A cold winter will kill young vegetative growth to the root crowns, but the vine resumes growth again in spring. Kudzu thrives through drought and hot temperatures, but continuous removal of all vegetative parts during extreme weather will kill kudzu over time. Only vines more than a yard above the ground in full sun will flower in late summer, and few fruiting pods develop viable seeds. However, vegetative reproduction occurs readily as trailing vines root at the nodes.
A native of Asia with many culinary and medicinal uses in the East, kudzu was introduced to America in large part in order to fight soil erosion. It quickly got out of control and became the most infamous type of rampantly uncontrollable, smothering vegetation.
Kudzu rapidly forms dense mats over the ground, shrubs, mature trees, and buildings. It kills or injures other plants by smothering them under a solid blanket of leaves that allow little light to penetrate. It can girdle shrubs and trees, break branches, and uproot entire trees with its weight. Everywhere it covers the landscape is a place where native plants cannot grow.