Giant Ragweed is, as its name suggests, a tall plant. It does not resemble the common ragweed. The leaves of giant ragweed are deeply cut with 3 lobes, hence the trifida. It prefers moist soil so is a problem in ditches and other areas with occasional water. Recently it has become a serious problem in soybeans because of marginal land being brought into production. It also is difficult to control with existing soybean herbicides. It has the same potential for causing allergenic reactions as the common ragweed.