Photographer: John M. Randall Affiliation: The Nature Conservancy Source: www.bugwood.org Copyright: CC BY-NC 3.0
Camelthorn (Alhagi maurorum) is a species of legume, native to desert ecoregions and is able to thrive in arid conditions due to its extensive root system. This plant grows low to the ground with a maximum height of 4 feet, and the majority of the growth occurring underground to utilize any available water sources nearby. Camelothorn flowers in June and July with pink to red blossoms all over the plant. The leaves are wedge-shaped, hairless, and 1/4 inch long. Stems are covered with spines or thorns and half moon seedpods are formed following the flowering season.
Camelthorn is an aggressive plant that is well known for out-competing native plant species and crops for water sources. Once it becomes established in an area it is able to grow in thick dense mats with protective spines that prevent other plants or animals from reaching water sources it is utilizing. The extensive root system of camelthorn allows it to tap nearby water sources at a more rapid rate that many native plants and crops. Further spread of camelthorn is often facilitated by seeds being mixed up with crop seeds such as alfalfa. Camelthorn has been noted as unpalatable to cattle and other grazing livestock and can negatively effect available grazing plants in agricultural fields.
Camelthorn is often propagated by seeds which are released from half-moon shaped seed pods formed following flowering. Seeds are scattered readily via water when the plant is established near streams and canals. Camelthorn is also spread accidentally by farmers with contaminated alfalfa seeds. Cereal and horticulture plants require repeated cultivation which further facilitates spread of camelthorn.
Camelthorn was introduced to the United States accidentally as seedlings in 1915. It was shipped unknowingly with a load of alfalfa seeds and was scattered into the wild, where it quickly became established.
Turanian Desert and the Iranian Plateau
Habitat: Camelthorn is capable of growing in very dry conditions, but has been seen growing along streams and canals in the United States.
U.S. Present: AZ, CA, CO, ID, NM, NV, TX, UT, WA
There are no biological control agents available to manage camelthorn. Mechanical control of the plant is difficult due to thorns and often unsuccessful due to the extensive root system. Tilling can provide temporary relief of the plant, but the root system alone can allow the plant to survive and regenerate. Chemical treatment has been proven effective in eradicating camelthorn, specifically the use of Picloram, but is not permitted for use in the state of California. Bromacil is also an effective management method of camelthorn and other similar broad leaf plant pests.
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.
Ball, W.S. and W.W. Robbins. 1933. Camelthorn, Alhagi camelorum (Fisch.). Monthly Bulletin of the California State Department of Agriculture 22:258-260.
Bottel, A.E. 1933. Introduction and control o camelthorn, Alhagi camelorum (Fisch.). Monthly Bulletin of the California State Department of Agriculture 22:261-263.
Hickman, J.C., ed. 1993. The Jepson Manual: Higher Plants of California. UC Press, Berkeley, CA.
Kerr, H.D., W.C. Robocker and T.J.Muzik. 1965. Characteristics and control of camelthorn. Weeds 13(2):156-163.