Reduced tillage and no-till systems provide favorable conditions for its development. In some instances, substituting preemergence herbicides for tillage has favored hemp dogbane spread. The root system is extensive, often penetrating 5 to 10 feet into the soil. Like the milkweed family, all parts of the plant contain a white, milky sap. Buds on hemp dogbane root system.
Hemp dogbane is listed as a poisonous plant in many references.
The milky sap does contain a cardiac glycoside similar to that found in digitalis species. Little is known concerning the toxicity of dogbane to livestock. Animals find the plant distasteful. Reported cases of poisoning are rare. Small greenish-white flowers are produced in clusters at the ends of branches from June through August.