Kudzu (Pueraria montana) — identification, habitat & look-alikes

Kudzu is a fast-growing Asian vine in the pea family that covers roadsides and forest edges across the southeastern US. It was first shown to Americans at the 1876 Centennial Exposition and later planted on a huge scale to stop soil erosion. Today it is considered a serious pest mainly in the Southeast.

Appearance

Growth form: A climbing, deciduous perennial vine in the pea family. The stems become somewhat woody with age, and a single can send up as many as 30 vines.
Leaves: Each leaf has three broad leaflets, about 3–6 in (8–15 cm) long, that may be smooth-edged or lobed. Leaves and stems are hairy.
Flowers: Purple to reddish-purple pea flowers, each about ½–¾ in (1–2 cm), packed in clusters up to 1 ft (30 cm) long. They have a sweet, grape-like scent.
Flowering time: Late summer.
Fruit: Flat, brown, hairy pods about 2 in (5 cm) long, each holding up to 10 hard seeds. Few of the seeds are viable.

Look-alikes

Hog peanutAmphicarpaea bracteata

Hog peanut and other native legume vines have much smaller leaflets and don't grow aggressively over whole trees.

Why they get mixed upBoth are vines with leaves made of three leaflets.

Wild grapesVitis

Grape leaves are single, undivided leaves, while each kudzu leaf is split into three leaflets.

Why they get mixed upBoth are big, leafy vines that climb over trees.

Bur cucumberSicyos angulatus

Bur cucumber has single, undivided leaves, not three separate leaflets.

Why they get mixed upIt also blankets shrubs and trees in summer.

Where it lives

Typical habitats: Forest edges
Roadsides
Disturbed or eroded land
Range: Found in about 32 states, mostly in the Southeast, with scattered patches as far north as the Boston and New York City areas and even Ontario, Canada. Native to Asia and some Pacific islands.
Preferred conditions: Does best in full sun on well-drained, disturbed or eroded soil, but can also creep into forests.

Growing it

Propagation: Spreads mostly by runners that root at every node, forming new root crowns. It can grow up to a foot (30 cm) a day in summer.
Toxicity: Not known to be toxic.

Name and classification

About the name: The kudzu found in the US is Pueraria montana var. lobata. The word kudzu is also used loosely for a few closely related Pueraria plants.

Conservation

Conservation: Rules vary by state. Some states regulate it as a ; for example, Indiana prohibits selling, moving, or planting it and requires landowners to get rid of it, and Washington lists it as a Class A noxious weed.
Threats: Smothers trees and ground plants and forms dense single-species patches that push out native plants. It can also harbor soybean pests and diseases.

Culture and stories

Culture and stories: In the 1930s the Soil Conservation Service paid landowners to plant kudzu to hold soil in place, and plantings peaked at more than a million acres by 1945. The government stopped promoting it in the 1950s.
Its reputation may outrun reality: estimates of how fast it spreads vary a lot, and some invasive plants such as Asian privet are a bigger problem in the US.
The flowers can be made into a jelly that tastes like grape jelly, and some places use goats or llamas to graze it down.