Bur Ragweed

General Information

Bur Ragweed · Ambrosia grayi (A. Nels.) Shinners · (formally known as Woollyleaf bursage, but aka woollyleaf povertyweed, woollyleaf franseria, or lagoonweed) is a perennial forb that is native to Kansas. It flowers from August through October, and reproduces through rhizomes and seeds. Its flowers are yellowish-green, and leaves are irregularly lobed and silvery, especially the lower surface. Its fruit is bur-like with 2 apical beaks and up to 13 other spines, formed by floral bracts (1.5-2 mm long), tips of spines slender, hooked at the tip; 2-seeded.


Bur Ragweed occurs in moist places of fields, rangeland, and roadsides. It often grows in saline soils. It occasionally accumulates nitrates, but it is unpalatable. This is an aggressive weed that spreads quickly, forms large colonies, and crowds out desirable plants. Tillage sometimes spreads the rhizomes.