Goldenrod is a native perennial that’s gaining popularity ... The true culprit that causes allergies in the autumn is ragweed (Ambrosia artemisiifolia), which blooms around the same time as ...

Western ragweed (Ambrosia psilostachya), on the other hand, is a perennial, so it could take years of mowing before it is eradicated. Because of this, herbicides are often a necessary evil when it ...

This staggering figure includes the San Diego ambrosia, a tenacious little perennial herb that clings by its rhizomes to only a handful of remaining sites in Southern California. The ambrosia ...