Great Ragweed

Great Ragweed, Ambrosia trifida

Great ragweed is a native annual that can be found throughout most of North America. Also known as giant ragweed, it is the tallest of the ragweeds and can reach between 1 m (3.2 ft) and 4.3 m (14 ft) in height. The large leaves are opposite and contain lobes to help distinguish it from other plants. Commonly found on roadsides, in old fields, and in poorly drained waste areas, great ragweed is decently adaptive. It can tolerate drier conditions, but significant drought damages ragweed.

Goldenrod (Left) is often confused with Ragweed (Right)

 As with other ragweeds, giant ragweed depends on wind pollination. In addition to often being considered a weed as it grows where it is unwelcome, ragweed is a bane to many allergy sufferers; however, it once placed an important role in the survival of Native tribes. The nutritious seeds, which contain about 19% edible oil, were a main grain to many tribes. Archaeological evidence links cultivation of the species in the central Mississippi Valley before introduction of maize. Although the ancient grain has fallen out of favor, the leaves remain of interest as an astringent.