Kansas Wildflowers and Grasses

BUFFALO BUR

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Solanum rostratum Dunal

Tallgrass Prairie National Preserve, Chase County, Kansas

Annual

Height: 8-28 inches

Family: Solanaceae - Nightshade Family

Flowering Period: May, June, July, August, September

Also Called:

Kansas thistle.

Stems:

Erect, single, much-branched, covered with tiny star-shaped hairs, armed with yellow spines.

Leaves:

Alternate, stalked, egg-shaped to broadly elliptic in outline, 1-2 times pinnately lobed or cleft, 1.5 to 6 inches long, 1 to 4 inches wide; lobes irregular, spiny, star-shaped hairy; tips rounded.

Inflorescences:

Racemes, 5-15-flowered, short-stalked, near ends of branches.

Flowers:

3/4 to 1 inch wide; calyces 5-lobed, very spiny; corollas somewhat flattened, 5-lobed, bright yellow; stamens 5, curving forward and down; anthers 4 yellow, alike, 1 purplish, enlarged, longer.

Fruits:

Berries, spherical, to 2/5 inch in diameter, enclosed by spiny calyx; seeds numerous, egg- to kidney-shaped, pitted, dark.

Habitat:

Disturbed sites, overgrazed pastures, waste areas, feedlots, and roadsides.

Distribution:

Throughout Kansas.

Origin:

Native

Comments:

The common name "buffalo bur" alludes to the plant's tendency to grow abundantly around bison wallows. Buffalo bur is drought resistant and extremely aggressive. It often thrives in actively-used cattle corrals. When mature, the main stem breaks near the ground and the plant rolls like a tumbleweed, scattering thousands of seeds.

Buffalo bur