Description and Variation:  Camelthorn is a deep-rooted, rhizomatous, perennial shrub, with roots that can extend six to seven feet into the ground. The spiny, intricately-branched shrub reaches 1.5 to four feet in height. The plant, which is grayish green and hairless, has simple, entire leaves that are alternately arranged. The leaf shape is oval to lance-shaped. The small (3/8 inch), pea-like flowers are pinkish purple to maroon and are borne on short, spine-tipped branches that arise from the leaf axils. The reddish-brown to tan fruits are constricted between the seeds, with a short narrow beak at the end.

Economic Importance:  Camelthorn is unpalatable and injurious to some animals. Because of its deep root system, camelthorn grows successfully in dry, rocky, saline soil, making it weedy in rangeland against preferred forage. The species is also a potential alfalfa seed contaminant.

Geographical Distribution:  Camelthorn is native to southeast Russia occurring primarily in dry open rangeland. It is not reported in our region by Hitchcock and Cronquist; however, it does appear on the noxious weed list for Idaho. Camelthorn now occurs in the Columbia Basin of central Washington, California, Nevada, Arizona, Australia, South Texas, and Africa.

Habitat:  Camelthorn occurs principally in deep moist soil, but it also occurs in dry, rocky, or saline soils. The plant is especially abundant along riverbanks, canals, and irrigation ditches, but it sometimes spreads into cultivated fields.

History:  Camelthorn was introduced into California from Turkey as an alfalfa seed contaminant and in packing materials around date palm offshoots. The only known population in the Pacific Northwest occurs on Bureau of Reclamation Land, Columbia Basin Project, Grant County, Washington. This infestation was first reported in 1956 along the lower Crab Creek drainage area and has since spread eastward toward Othello, where it now encompasses 20-25 sections of land.

Growth and Development:  Camelthorn is a rhizomatous perennial that can give rise to aerial shoots up to 25 feet away from parent plant.

Reproduction:  The species spreads by seeds and rhizomes.

Response to Herbicides: None listed

Rationale for Listing:

1. Camelthorn has been shown to be a severe rangeland pest in other areas of the United States (El Paso County, Texas).
2. Washington’s infestation has shown aggressive spread in our area and borders on a major state highway, which could provide for its rapid spread to other areas.
3. Camelthorn infestations are presently limited to a size which makes an eradication program feasible.

State of California Detection Manual. 1982. Camelthorn.

Parker, K. F. An Illustrated Guide to Arizona Weeds. University of Arizona Press. Tucson, AZ.

Weeds of California.