Virginia Tech Weed Identification Guide

Kudzu: Pueraria lobata

Weed Description: An invasive perennial vine with trifoliate leaves that was initially brought to the Unites States from Japan in 1876 as a soil cover to prevent erosion.  Kudzu is one of the most common and troublesome weeds of rights-of-way, power lines, roadsides, and forests, and now invades an estimated 2,00,000 acres in the southeastern United States.  It is common for this weed to completely overgrow all trees and other vegetation once it is established in an area.  It is estimated that a single acre of kudzu would expand to 5,250 acres if left uncontrolled for 100 years.
Seedlings:  Cotyledons are oval to oblong.  First true leaves are covered with short bronze hairs and are arranged oppositely.  All subsequent leaves consist of 3 leaflets (trifoliate) and each set of 3 leaflets are arranged alternately along the stem.

Roots:  Both fibrous and tuberous roots occur.

Leaves:  Consist of 3 leaflets (trifoliate leaves).  Each set of 3 leaflets is arranged alternately along the stem.   All leaflets occur on petioles, however the lateral leaflets are on very short petioles (less than 1/2 inch), while the center leaflet occurs on a petiole approximately 3/4 inch long.  All leaves are ovate in outline, hairy, and lobed.  Lateral leaflets are usually lobed on one side only while the center leaflet is usually lobed on both sides.
Stems:  Climbing on other vegetation or trailing along the ground.  When young, stems are covered with stiff bronze hairs but these become much less common on older plants.  Stems may become woody when mature.

Flowers:  Occur in racemes that arise from the area between the leaflet petiole and the stem (axillary regions).   Each raceme is approximately 4 to 8 inches long and is reddish purple in color.   Flowers are often inconspicuous due to the dense vegetation that often covers them, but generally emerge in August-September in Virginia.

Fruit:  A pod, approximately 1 1/2 to 2 inches long that contains many kidney bean-shaped seed.

Identifying Characteristics:   The rapid growth, climbing or trailing nature,  and invasive habit of kudzu make it easy to distinguish from most other weeds.  The hairy leaves and stems and lobed leaves are also characteristics that help in the identification of kudzu.