Kudzu Identification: Three Hairy Leaflets, Purple Flowers

Kudzu is a hairy, climbing vine whose leaves are split into three broad leaflets, each 3 to 4 inches long, and which blankets trees, poles and roadsides in summer. King County's noxious weed program and NC State Extension give these marks:

• Leaves: compound, with three leaflets, oval to almost heart-shaped, dark green; Wikipedia adds that each leaflet usually has two or three lobes and hair on the underside.
• Stems: hairy, spreading in every direction; older vines become woody with rough, dark brown bark. King County gives 90-plus feet of vine; NC State gives up to 100 feet.
• Flowers: purple to reddish-purple, pea-like, half to three-quarters of an inch, in upright clusters up to a foot long, from late summer into early fall. Wikipedia calls them fragrant.
• Pods: flat, brown and covered in long hairs; about 2 inches (King County) or 1.3 to 3 inches (NC State).
• Roots: massive taproots up to 7 inches in diameter and several feet long (NC State).

In winter the leaves drop, because kudzu is deciduous, but the woody vines and dead leaf mats stay on whatever they covered.

Several vines carry leaves of three. Check the leaflet size, the hairs and the flowers:

• Poison ivy: leaflets 3 to 12 cm, almond-shaped, with the middle leaflet on a noticeably longer stalk; climbing stems look hairy because of many aerial rootlets gripping the bark; grayish-white berry-like fruit from August to November (Wikipedia). Wikipedia's poison ivy article itself names kudzu as a look-alike and separates it by its bigger leaflets with hairy margins. Poison ivy causes an itchy rash in most people, so do not touch a vine you have not identified.
• Virginia creeper: may show three leaflets on young growth but usually has five (Wikipedia).
• Box elder: three leaflets but opposite leaves on the stem; kudzu and poison ivy leaves are alternate.
• Hog peanut: three leaflets on a thin twining annual-to-perennial vine with pink to white flowers from late summer to autumn (Wikipedia); it does not build woody stems.

Only kudzu combines large hairy leaflets, fuzzy stems, purple pea flowers and flat hairy pods.

Kudzu favors open, disturbed, sunny ground: roadsides, rights-of-way, forest edges and old fields (Invasive Plant Atlas), and well-drained, eroded or sandy soils (King County). Wikipedia names Georgia, Alabama and Mississippi as the most heavily infested states and reports kudzu in more than 22 states, now reaching Texas, Oklahoma and northern states (NC State Extension).

How fast it spreads is disputed. Wikipedia sets a US Forest Service figure of 2,500 acres a year (2015) against a USDA figure of 150,000 acres a year (2009), and explains that kudzu's habit of growing on sunny roadside edges makes it look more widespread to drivers than it is. Total cover in the Southeast is estimated at about 7.4 million acres.

Wikipedia's timeline of kudzu in the United States:

• 1876: shown at the Centennial Exposition in Philadelphia
• 1883: introduced to the Southeast at the New Orleans Exposition
• 1930s: the Civilian Conservation Corps distributed 85 million seedlings for erosion control
• 1953: the USDA removed it from its list of suggested cover plants
• 1970: officially listed as a weed
• 1997: placed on the Federal Noxious Weed List (removed in 2000, though still listed by various states)

In Washington State it is a Class A noxious weed that must be eradicated and is illegal to buy or sell (King County).

Patches can be killed, but only by killing the root crowns and then checking for regrowth. King County notes that one crown can send up as many as 30 vines and that vines root at their nodes to form new crowns. Methods from the sources:

• Dig out the root crown. King County says the vines die once the crown is removed; bag the crowns for the trash and compost the rest.
• Repeated mowing or grazing during the growing season works on small or new patches but needs ongoing effort (King County; NC State).
• Cut-stump treatment with 50% triclopyr applied within 3 minutes of cutting, for established vines (NC State).
• Foliar spray of 2 to 3% triclopyr or glyphosate with a surfactant for large infestations, followed by crown removal (NC State). King County calls repeated foliar spraying through the season the most effective method.

All methods need follow-up monitoring for regrowth (NC State). Read and follow the herbicide label, and in Washington State contact your county noxious weed program first.

Yes, mostly outside the US. Wikipedia lists these uses:

• Starch: the starchy root has been used in East Asia for a very long time; kudzu starch thickens or sets food like arrowroot or tapioca and goes into Japanese sweets and noodles.
• Fiber: kudzu cloth, ko-pu, was historically one of China's three major textiles with silk and ramie.
• Livestock feed, erosion control and possible biofuel use.
• Supplements: it is considered a medicinal plant and sometimes sold in health food stores.

Before eating any wild plant, have the identification confirmed by someone who knows local plants, and ask a doctor before taking any herbal supplement.

One photo of a vine-covered hillside cannot separate kudzu from other vines. Take three: a whole leaf with all three leaflets and its stalk, a close-up of the stem showing its hairs, and any flowers or pods. NatureLens can suggest a species from these photos, with free scans every day; if the answer is kudzu and you live outside the Southeast, report it to your county or state weed program.

Research and drafting for this page used AI assistance. Every measurement, date and claim was then checked against the sources listed below, which were opened and read on 2026-09-25. Where two sources give different numbers, both are shown.