Ragweed (Ambrosia artemisiifolia)

Ah--choo! Ah--choo! Does this weed grow in your yard? It may not bother you, but could give your neighbors hay fever.

Racemes or spikes of tiny green "bells" contain the staminate (male) flowers. Each little bell is a five-lobed corolla with five stamens.

The pistillate (female) flowers are few, and are in the axils of the upper leaves. They have no corolla, only a forked pistil with an inferior ovary, surrounded by a ribbed calyx tube which becomes the achene (seed).  These flowers depend upon the wind to bring the fine yellow grains of pollen for fertilization.

Ragweed is a coarse annual with leaves deeply bipinnately dissected, lower ones opposite, upper ones alternate. The plant is named for the raggedy shape of its leaves.

It is a member of the Aster Family,  Asteraceae.  Strangely, its scientific name, Ambrosia, was the delicious food eaten by the mythical Greek gods to make them live forever.