| Gutierrezia sarothrae | |
|---|---|
 | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Gutierrezia |
| Species: | G. sarothrae |
| Binomial name | |
| Gutierrezia sarothrae | |
| Synonyms[1][2] | |
List of Synonyms
| |
Gutierrezia sarothrae is a species of flowering plant in the familyAsteraceae known by the common namesbroom snakeweed,broomweed,snakeweed, andmatchweed. It is asubshrub native to much of the western half ofNorth America, fromwestern Canada to northernMexico, 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 ofsaponins.
The species was utilized by variousNative American groups for medicinal and other purposes.
Gutierrezia sarothrae is aperennial subshrub that ranges from 20 to 100 centimetres (8 to39+1⁄2 inches) in height. The stems are green to brown, bushy, and herbaceous, and branch upwards from a woody base.[3] The stems die back during dormancy, giving the plant its broom-like appearance.[3] They range from smooth to having some short hairs, and may beresinous and therefore sticky when touched.[4] As the stems are about the same length, this causes the plant to often appear domed or fan-shaped when flowering.[5] Theleaves are alternate and linear, and5 to 63 millimetres (1⁄4 to2+1⁄2 in) long and1 to 3 mm (1⁄16 to1⁄8 in) wide.[4][6] The lower leaves are usually shed before the plant flowers.[5] During its first year of growth, the plant produces a long, woodytaproot, and numerouslateral roots as the plant matures.[7]
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,[6] at the end of the stems from mid-July to September.[3][5][8] The flowers are pollinated by various insects, resulting in an oval fruit covered withchaffy scales.[3] The plant reproduces from seeds, which are light, densely hairy, and wind-dispersed.[3][7] A single plant is capable of producing over 9,000 seeds annually, although most ripe seeds fall beneath the parent plant.[7] Seeds can remain viable in the soil for several years; under laboratory conditions seeds have remained viable for at least two years.[7]
G. sarothrae is commonly confused withrabbitbrush, but can be distinguished by the presence of ray flowers, which rabbitbrush plants do not have.[3] It is also similar to littlehead snakeweed (G. microcephala), which has only 1–3 of both ray and disk flowers.[6]
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.[6] It has also been called 'turpentine weed' due to its odour.[6]
A native North American plant,G. sarothrae is found throughout west-central Canada (thePrairie Provinces, the western and centralUnited States (theGreat Plains and regions to the west), andnorthern Mexico as far south asZacatecas andBaja California Sur.[9][10] Due to its efficient water use anddrought 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.[3][7] The species is very adaptable, and can be found in a variety ofecoregions, includingpinyon–juniper woodlands,desert shrublands, and sagebrush-grasslands.[7] It can survive in a wide variety of soil types with full sun and good drainage,[4] but growth is reportedly best in clay loams ofalluvial slopes, and shallow, rocky, or sandy soil, and is poor insaline oralkaline soils.[7]
G. sarothrae is a poor quality browse for most largeungulates.[11] It is important topronghorn antelope in some areas, especially during spring and summer, and can comprise up to 28% of the pronghorn antelope's diet.[4] The plant is of little value tocattle andhorses, but can be a fair quality winter browse for domesticsheep when there is little access to green forage.[3]
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 inmesquite sand dunes.[12] It has been rated by theU.S. Fish and Wildlife Service as low to medium for erosion control potential, low for short-termrevegetation potential, and low to medium for long-term revegetation potential.[13]
G. sarothrae is one of the most widespread and damagingrangeland weeds,[14] and can displace desirable vegetation if not properly managed.[4] This displacement may be caused by livestock grazing, drought, orfire suppression. The plant quickly invadesovergrazed rangeland, as cattle often leave it untouched whileovergrazing grasses.[15] Because of this, an abundance ofG. sarothrae is considered to be an indicator of rangeland deterioration. It is afire-intolerant species, and is severely harmed or killed by fire; immediately after a fire it may be completely removed from an area.[16] However, seeds can remain viable if in the soil, often causingG. sarothrae densities to increase after a fire.[4] This may make it necessary to burn at five to ten year intervals in order to reduce its populations.[17]
Herbicide effectiveness is variable; when herbicide application is effective, populations are controlled for up to five years.[15] Mechanical control is generally ineffective; hoeing the plants just below the soil can be effective, but may be impractical in stony soil.[15] Biological control has also been studied, with a combination of an Argentinean root-boring weevil,Heilipodus ventralis, and an Argentinean moth root-borer,Carmenta haematica, found to be an effective method of control.[14]
G. sarothrae can be toxic to domestic sheep,goats, and cattle when consumed in large quantities,[11] although domestic goats are moderately resistant to its effects.[18] Its toxicity is due primarily tosaponins, which can cause illness, death, or abortion, as well as toalkaloids,terpenes, andflavonols in the plant.[19] The species is also a facultative absorber ofselenium, which can cause illness or death in large amounts.[3][20] As little as 9 kilograms (20 pounds) of freshG. sarothrae consumed by cattle in seven days can cause miscarriages, and in cattle, sheep, and goats consuming ten to 20% of their body weight in two weeks can cause death.[21] Toxicity is generally higher during periods of rapid growth, such as early leaf development, and when grown on sandy rather than oncalcareous orclay soils.[11][21]
G. sarothrae was used by theNative Americans of theGreat Plains for various reasons.[3][4][5] TheComanche bound the stems together to make brooms. TheBlackfoot used the roots in an herbal steam as a treatment for respiratory ailments. Adecoction of the plant was used by theLakota to treat colds, coughs, and dizziness, while a concentrate made from the flowers was used by theDakota as a laxative for horses. TheNavajo rubbed the ashes of the plant on their bodies to treat headaches and dizziness, and also applied the chewed plant to wounds, snakebites, and areas swollen by insect bites and stings. TheZuni used aninfusion of the blossoms as adiuretic and to "make one strong in the limbs and muscles",[22] and an infusion of the whole plant was used topically for muscle aches.[23]
