Gutierrezia sarothrae is a species of flowering plant in the family Asteraceae known by the common names broom snakeweed, broomweed, snakeweed, and matchweed. It is a subshrub native to much of the western half of North America, from western Canada to northern Mexico, and can be found in a number of arid, grassland, and mountain habitats. It can be toxic to livestock in large quantities, due mainly to the presence of saponins. The species was utilized by various Native American groups for medicinal and other purposes.
Description Gutierrezia sarothrae is a perennial subshrub that is typically 10 to 60 centimeters (4 to 24 in) in height, but can sometimes reach as much as 100 cm (39 in). Its stems are brown at their base and are green to tan in color higher up on the plant. They branch freely from the woody caudex at the base forming a rounded shape. The stems die back during dormancy, giving the plant its broom-like appearance. They range from smooth to having some short hairs, and may be resinous and therefore sticky when touched. As the stems are about the same length, this causes the plant to often appear domed or fan-shaped when flowering. The leaves are alternate and linear, and 5 to 63 millimetres (1⁄4 to 2+1⁄2 in) long and 1 to 3 mm (1⁄16 to 1⁄8 in) wide. The lower leaves are usually shed before the plant flowers. During its first year of growth, the plant produces a long, woody taproot, and numerous lateral roots as the plant matures.
Dense clusters of 3–7 small, yellow ray and 2–6 tiny disk flowers form in clusters, 3–6 mm (1⁄8–1⁄4 in) in length, at the end of the stems from mid-July to September. The flowers are pollinated by various insects, resulting in an oval fruit covered with chaffy scales. The plant reproduces from seeds, which are light, densely hairy, and wind-dispersed. A single plant is capable of producing over 9,000 seeds annually, although most ripe seeds fall beneath the parent plant. Seeds can remain viable in the soil for several years; under laboratory conditions seeds have remained viable for at least two years. G. sarothrae is commonly confused with rabbitbrush, but can be distinguished by the presence of ray flowers, which rabbitbrush plants do not have. It is also similar to littlehead snakeweed (G. microcephala), which has only 1–3 of both ray and disk flowers.
Taxonomy Gutierrezia sarothrae was scientifically named and described as Solidago sarothrae by Frederick Traugott Pursh in 1813. It was moved to the genus Gutierrezia by Nathaniel Lord Britton and Henry Hurd Rusby in 1887. It is classified in the Asteraceae. It has no accepted subspecies or varieties, but it has 33 synonyms.
Etymology The genus name, Gutierrezia, was selected by Lagasca, but he did not specify who was being honored. According to research by Kathleen H. Keeler, a likely person associated with the Royal Botanical Garden of Madrid during the time period was Pedro Gutiérrez Bueno (1745-1826). The species name, sarothrae, is related to sarothron, "broom", and sarein, "to sweep", describing the numerous herbaceous branches of this plant. The common name matchweed refers to the appearance of the stems and flower heads to matches, whereas broomweed refers to its use as a broom and snakeweed refers to its medicinal use to treat snakebites. A related name, sheep weed, is for its folk use as a treatment for sheep bitten by rattlesnakes. It is likewise known as yerba de la vibora, rattlesnake weed, by Spanish speakers. It has also been called turpentine weed due to its odor. An occasional common name for the species is golden broomweed.
Distribution and habitat A native North American plant, G. sarothrae is found throughout west-central Canada (the Prairie Provinces, the western and central United States (the Great Plains and regions to the west), and northern Mexico as far south as Zacatecas and Baja California Sur. Due to its efficient water use and drought tolerance, it is able to survive in arid and semi-arid sites, such as rocky plains, dry foothills, ridgetops, mountain slopes, and in semi-desert valleys. The species is very adaptable, and can be found in a variety of ecoregions, including pinyon–juniper woodlands, desert shrublands, and sagebrush-grasslands. It can survive in a wide variety of soil types with full sun and good drainage, but growth is reportedly best in clay loams of alluvial slopes, and shallow, rocky, or sandy soil, and is poor in saline or alkaline soils.
Ecology G. sarothrae is a poor quality browse for most large ungulates. It is important to pronghorn antelope in some areas, especially during spring and summer, and can comprise up to 28% of the pronghorn antelope's diet. The plant is of little value to cattle and horses, but can be a fair quality winter browse for domestic sheep when there is little access to green forage. Under natural conditions, G. sarothrae quickly invades disturbed areas, and can minimize soil erosion; for example, it is reportedly able to stabilize loose windblown soils in mesquite sand dunes. It has been rated by the U.S. Fish and Wildlife Service as low to medium for erosion control potential, low for short-term revegetation potential, and low to medium for long-term revegetation potential.
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