Enantiomers of chiral exogenous chemicals are of increasing interest in the field of environmental chemistry. Most pesticides, along with their degradation products, become widely dispersed in ecosystems and can be found in various food chains. Chiral pesticides may have enantioselective ecotoxic effects on nontarget plants, and can also be enantioselectively metabolized by plants. In this book, enantioselective toxic effects of chiral herbicide diclofop acid were evaluated using nontarget plants. Understanding the different plant biochemical processes in which exogenous chiral chemicals are involved can greatly help the development of appropriate synthetic chemicals and could reduce the environmental risks.