Page author: David Giblin
Solanum rostratum
buffalo bur, horned nightshade

Distribution: Widely distributed throughout Washington, where it is considered a noxious weed; widely distributed throughout North America.

Habitat: Roadsides and other disturbed areas, often where dry.

Flowers: June-September

Origin: Introduced from central US

Growth Duration: Annual

Conservation Status: Not of concern

Pollination: Bumblebees, bees, flies


Coarse, erect, branching annual 3-10 dm. tall, the herbage and flowers stellate-pubescent, the calyces, stems, and often the leaves covered with yellow spines 3-12 mm. long.


Leaves petiolate, 6-20 cm. long and 2-7 cm. wide, deeply pinnately lobed, the lobes broad and round-tipped, and may again be shallowly lobed.


Inflorescence of several 3- to 15-flowered racemes, attached along the stem or opposite the leaves, elongating up to 1.5 dm. in fruit; corolla rotate, light yellow, with 5 short lobes, 2-3 cm. wide; stamens 5, with one anther much longer than the other 4; style solitary; ovary superior.


Fruit a berry

Accepted Name:
Solanum rostratum Dunal
Publication: Hist. Nat. Solanum 234-235, pl. 24. 1813.

Synonyms & Misapplications:
Androcera rostrata (Dunal) Rydb.
Solanum cornutum Lam., misapplied
Additional Resources:

PNW Herbaria: Specimen records of Solanum rostratum in the Consortium of Pacific Northwest Herbaria database.

WA Flora Checklist: Solanum rostratum checklist entry.

OregonFlora: Solanum rostratum information.

E-Flora BC: Solanum rostratum atlas page.

CalPhotos: Solanum rostratum photos.

USDA Plants: Solanum rostratum information.

32 photographs:
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