Ambrosia dumosa, the burro-weed or white bursage, a North American species of plants in the family Asteraceae. It is a common constituent of the creosote-bush scrub community throughout the Mojave Desert of California, Nevada, and Utah and the Sonoran Desert of Arizona and northwestern Mexico (Baja California, Baja California Sur, Sonora, Chihuahua).[3][4][5][6]
| Ambrosia dumosa | |
|---|---|
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Scientific classification 
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Angiosperms |
| Clade: | Eudicots |
| Clade: | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Genus: | Ambrosia |
| Species: | A. dumosa
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| Binomial name | |
| Ambrosia dumosa | |
| Synonyms[1][2] | |
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Ambrosia dumosa has been studied to determine allelopathic interactions with creosote bush, Larrea tridentata, which produces a chemical that inhibits the growth of A. dumosa.[citation needed] Other studies have suggested that A. dumosa roots produce a chemical that causes them to grow away from conspecific roots, preventing competition for water resources. In addition to burro-weed, A. dumosa is also commonly called white bursage, and burrobush.
Description
editAmbrosia dumosa or white bursage is a form of ragweed, is a highly branched shrub 20 to 90 cm in height. The younger stems are covered with soft gray-white hairs. Approximately obovate leaves are 1 to 3 times pinnately compound or deeply lobed and generally clustered on short branches. The leaves are 0.5 to 4 cm long and also covered in soft gray-white hairs.[3]
Its inflorescence is yellow with staminate and pistillate headson a single plant (monoecious). Staminate heads have many flowers and are 3 to 5 mm in diameter with a 5 to 8 lobed involucre. Pistillate heads are 2 flowered and lack corollas.[3]
Ambrosia dumosa has spherical bur-like fruits ranging in color from golden to purple to brown. Along with microscopic hairs, the fruit has 12 to 35 flat and straight spines which are 5 to 9 mm in length and scattered over the surface.[7][3]
Ambrosia dumosa becomes dormant during drought, losing all of its leaves to prevent water loss by transpiration; drought deciduous. During this time, it can still be recognized by the presence of longitudinal stripes on smaller stems.[7]
Like other types of Ambrosia, this is a ragweed, wind-blown pollen from burro-weed can cause serious allergic reactions. Increasing cases in Mojave Desert as the population grows from Joshua Tree, CA to Las Vegas, NV.
References
edit- ^ Tropicos, Ambrosia dumosa (A. Gray) W.W. Payne
- ^ The Plant List, Ambrosia dumosa (A.Gray) W.W.Payne
- ^ a b c d Flora of North America Vol. 21 Page 13 Bursage Ambrosia dumosa (A. Gray) W. W. Payne, J. Arnold Arbor. 45: 422. 1964.
- ^ Biota of North America Program 2014 county distribution map
- ^ Calflora taxon report, University of California, Ambrosia dumosa (A. Gray) Payne Burrobush, burro weed, white bursage
- ^ Tropicos, specimen listing for Ambrosia dumosa (A. Gray) W.W. Payne
- ^ a b Allen A.Schoenerr, Allen A. 1992. A Natural History of California. Berkeley: University of California Press. ISBN 0-520-06922-6
- Jepson Manual Treatment: Ambrosia dumosa
- C.Michael Hogan, species editor. 2010. Ambrosia dumosa. Encyclopedia of Life
