Ambrosia confertiflora is a North American species of ragweed known by the common name weakleaf bur ragweed.Calflora taxon report, University of California, Ambrosia confertiflora DC. weak leaved burweed, weakleaf burr ragweed
Description 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.Jepson Manual TreatmentFlora 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.
Distribution and habitat 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.Biota of North America Program 2014 county distribution map It is also naturalized in various other regions, and has been declared a noxious weed in AustraliaState of Victoria, Victorian Resources Online, Map of Potential Distribution of Burr ragweed (Ambrosia confertiflora) in VictoriaAtlas of Living Australia, Ambrosia confertiflora DC. Burr RagweedSouthern Tablelands and South Coast Noxious Plants Committee (New South Wales), burr ragweed and in Israel. It grows in disturbed sites.
References
External links Calflora Database: Ambrosia confertiflora (Weak leaved burweed, Weakleaf burr ragweed) Jepson Manual eFlora (TJM2) treatment of Ambrosia confertiflora UC Calphotos Photo gallery: Ambrosia confertiflora