Description and Variation:  Buffalobur is a low growing, yellow-flowered, spined, hairy annual. The stems (mostly branching in the upper part), are erect and bushy, 1/2 to two feet long. The entire plant, except the for the flower petals, is covered by straight yellow spines, 1/8 to 1/2 inch long. The leaves are alternate and two to six inches long including the stalks. Each leaf is irregularly cut into five to seven lobes, and often these are two to five lobed. The leaves are covered by short yellow star-like hairs, and the midribs, veins, and leaf stalks are spiny. The yellow flowers are five-lobed, wheel-shaped, 1 to 1.5 inches across, in few flowered clusters on spiny flower stalks. The calyx is covered by spines; it enlarges and forms a spiny bur, enclosing and completely covering the seedpod. The seeds are almost circular, 1/2 inch or slightly more in diameter, brown to reddish brown, flattened, irregularly angled, with a finely pitted surface. To identify buffalobur, look for the tomato-like yellow flowers and the unique, extremely prickly leaves, stems and fruits.

Economic Importance:  Buffalobur is considered to be a "nuisance weed" of barnyards, corrals, etc. The burs may cause damage and considerable loss in wool value in sheep. Buffalobur is considered noxious on farms and rangelands.

Geographical Distribution:  Buffalobur is native to the Midwest, where it is known to be highly aggressive and invasive. It is widely distributed in the western United States and is common on disturbed sites and sandy soils. There have been frequent repetitive introductions in central and eastern Washington, but buffalobur has never become established. That buffalobur has never established in Washington is due to aggressive control measures taken against the plant rather than its lack of ability to survive in Washington.

Habitat:  Buffalobur grows in fields, overgrazed pastures, yards, roadsides, waste areas, and  barn yards. Although it is adapted to sandy soils, it will also grow on dry hard soils to rich moist soils of cultivated fields.

History:  Buffalobur is a native North American species; its range extending from central Mexico northward across the Great Plains of the United States. It is widely introduced elsewhere, including the U.S.S.R. and Australia. Repeatedly introduced into the pacific northwest, buffalobur usually appears in gardens, where it was planted with flower or vegetable seeds. Land managers found it near Penticton, British Columbia, following reseeding of rangeland. Occasionally, plants sold as tomato seedlings have matured into buffalobur. The name "buffalobur" dates back to the time of settlement of the Great Plains when the plant grew abundantly in the disturbed soil of buffalo wallows. Buffalo carried the burs great distances in their shaggy coats.

Growth and Development:  Buffalobur is an annual species. The plants bloom in late June to early August and the seeds mature from July to October.

Reproduction:  Buffalobur reproduces by seeds only.

Response to Herbicides:  2,4-D plus Banvel can control buffalobur: Buffalobur is moderately susceptible to 2,4-D when seedlings are immature. It becomes very resistant to 2,4-D after flowering. A combination of 2,4-D plus Banvel usually provides more complete control than either herbicide alone. Apply 2 quarts 2,4-D (3.8 pound acid equivalent per gallon) plus 1 pint Banvel per acre before plants bloom. Always follow label instructions.

Response to Cultural Methods:  Prevent seed production of buffalobur by repeated, close mowing or by hoeing scattered plants before blossoms appear.

Biocontrol Potentials:  None known.

References:

Bassett, I.J. and D.B. Munro. 1986. The biology of Canadian weeeds.78. Solanum carolinense L. and Solanum rostratum Dunal. Can. J. Plant Sci. 66:977-991.

Dennis, LaRea J. 1980. Gilkey's Weeds of the Pacific Northwest. Oregon State University Press. Corvallis, Oregon. page 254.

Fawcett, R.S. and M.D.K. Owen. 1984. Weed control -- Buffalo Bur (Solanum rostratum Dunal). Pm-744. Iowa State Univ. Coop. Ext. Serv., Ames 2 pp.

Hovanic Toxicity Notes.

Nelson, E.W. and O. Burnside, eds. 1979. Nebraska Weeds. Nebraska Dept. of Agric., Lincoln. pp.167.

Pacific Northwest Weed Control Handbook. 1991.

Poisonous Plants of United States and Canada.

Rushing D.W., D.S. Murray and L.M. Verhalen. 1985. Weed interference with cotton (Gossypium hirsutum). I. Buffalobur (Solanum rostratum). Weed Sci. 33:810-814.

Wax, L.M., R.S. Fawcett and D. Isely, eds. 1981. Weeds of the North Central States. North Central Reg. Res. Publ. No. 281, Agric. Exp. Sta. Bull. 772. Univ. of Illinois, Urbana. pp. 162-163.

Weeds of California. pp. 389-390.

Weeds of the North Central States.

Whalen, M.D. 1979. Taxonomy of Solanum setion androceras. Gentes Herbarum 11 (6):359-426.

Whitson, T.D., ed. 1987. Weeds and Poisonous Plants of Wyoming and Utah. Coop. Ext. Serv., Univ. of Wyoming, Laramie, pp. 118-119.

This page was last updated 03/31/07