Buffalobur

Solanum rostratum

Alternate names
Kansas thistle, Texas thistle, Beaked nightshade

Weed Description
An annual with deeply lobed leaves and spines. May grow to 2 feet in height. Buffalobur is found throughout the United States, but is relatively rare in Virginia.

Seedlings
Cotyledons often purple-tinged beneath, without hairs or often with gland-tipped hairs on the margin and midvein beneath. Stems below the cotyledons (hypocotyls) are also often purple-tinged, succulent, and hairy.

Leaves
Alternate, egg-shaped in outline and widest at the apex (obovate), deeply lobed, 2 to 5 inches long, petiolate, with stiff straight hairs on the upper surface and dense star-shaped hairs on the lower surface. Leaf venation is also very prominent.

Stems
Erect or spreading, up to 2 ft tall, with star-shaped hairs and many yellow spines.

Flowers
Bright yellow in color, 5-parted, and approximately 1 inch wide.

Fruit
A berry, 8-12 mm in diameter that is enclosed by a spiny calyx.

Roots
Fibrous tap root system.

Identifying Characteristics
The deeply lobed leaves with prominent white veins, bright yellow flowers, and foliage and fruit that are covered with spines are all characteristics that help to distinguish buffalobur from most other weeds.

Office of Programs

University of Missouri

Buffalobur

Solanum rostratum