Ambrosia confertiflora is native to much of northern Mexico (from Sonora to Tamaulipas) and the southwestern United States from California east as far as Kansas, Oklahoma, and central Texas. It is also naturalized in various other regions and has been declared a noxious weed in Australia.
Ambrosia confertiflorais a perennial herb reaching heights between 30 centimeters and nearly two meters with bristly, fuzzy green to brown erect stems. The multilobed fuzzy leaves have blades which can be nearly 16 centimeters long and are borne on petioles with lobed, winglike appendages. As in other ragweeds, the inflorescence has staminate (male) and pistillate (female) flower heads. The pistillate heads yield one or two fruits which are burrs up to half a centimeter long and covered in short spines.
- The Plant List Ambrosia confertiflora DC.
- Calflora taxon report, University of California, Ambrosia confertiflora DC. weak leaved burweed, weakleaf burr ragweed
- Biota of North America Program 2014 county distribution map
- State of Victoria, Victorian Resources Online, Map of Potential Distribution of Burr ragweed (Ambrosia confertiflora) in Victoria
- Atlas of Living Australia, Ambrosia confertiflora DC. Burr Ragweed
- Southern Tablelands and South Coast Noxious Plants Committee (New South Wales), burr ragweed
- Jepson Manual Treatment
- Flora of North America Vol. 21 Page 18 Ambrosia confertiflora de Candolle in A. P. de Candolle and A. L. P. P. de Candolle, Prodr. 5: 526. 1836.
- Calflora Database: Ambrosia confertiflora (Weak leaved burweed, Weakleaf burr ragweed)
- Jepson Manual eFlora (TJM2) treatment of Ambrosia confertiflora
- USDA Plants Profile for Ambrosia confertiflora (weakleaf bur ragweed)
- UC Calphotos Photo gallery: Ambrosia confertiflora
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