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.