File Size: 59 KB
Solanum rostratum  Dunal
Tallgrass Prairie National Preserve, Chase County, Kansas
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.

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