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Ambrosia dumosa, the burro-weed or white bursage, a North American species of plants in the sunflower family. 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
Ambrosia dumosa 2.jpg
Scientific classification edit
Kingdom: Plantae
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Ambrosia
Species:
A. dumosa
Binomial name
Ambrosia dumosa
Synonyms[1][2]
  • Franseria albicaulis Torr.
  • Franseria dumosa A.Gray
  • Gaertnera dumosa (A.Gray) Kuntze
  • Gaertneria dumosa (A.Gray) Kuntze

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 burrow-weed, A. dumosa is also commonly called bur sage, burro weed, and burro bush.

DescriptionEdit

Ambrosia dumosa, 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 population grows from Joshua Tree, CA to Las Vegas, NV.

ReferencesEdit

  1. ^ Tropicos, Ambrosia dumosa (A. Gray) W.W. Payne
  2. ^ The Plant List, Ambrosia dumosa (A.Gray) W.W.Payne
  3. ^ 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.
  4. ^ Biota of North America Program 2014 county distribution map
  5. ^ Calflora taxon report, University of California, Ambrosia dumosa (A. Gray) Payne Burrobush, burro weed, white bursage
  6. ^ Tropicos, specimen listing for Ambrosia dumosa (A. Gray) W.W. Payne
  7. ^ a b Allen A.Schoenerr, Allen A. 1992. A Natural History of California. Berkeley: University of California Press. ISBN 0-520-06922-6

External linksEdit