Ragweed

Description

Bassia scoparia is a large annual herb in the family Amaranthaceae (sensu lato) native to Eurasia. It has been introduced to many parts of North America, where it is found in grassland, prairie, and desert shrub ecosystems. Its common names include ragweed, summer cypress, mock-cypress, kochia, belvedere, burningbush,Mexican firebrush, and Mexican fireweed, the provenance of the latter three names being the herb's red autumn foliage. The fruit of Bassia scoparia with the calyx attached is dull brown, but when hulled reveals dull black seeds, or dark to blackish-brown seeds in some escaped regions such as Europe. The seeds are dispersed by wind and water, and it is transported when the whole plant detaches and rolls on the wind as a tumbleweed. The seed does not persist in the soil seed bank, dying within about a year if it fails to germinate. The species is a C4 plant, specifically of the NADP-ME type. B. scoparia develops herbicide resistance unusually quickly and quadruple-resistant populations have developed in North America.