Hemp dogbane Apocynum cannabinum L.
Family: Apocynaceae (Dogbane family)
Life cycle: Perennial reproducing by seed and vegetative rootstalks
Native status: Native to North America
Habitat: Crop fields, pastures, roadsides
General description: Erect plant up to 3 to 4 ft tall; upper half of stem is branched; leaves are ovate, 2 to 3” long, and arranged opposite. Small white to greenish white flowers, produce long, slender seed pods. Glabrous stems.
Key ID traits: Opposite leaves, 2-5 in long with entire margins; secretes a milky sap when bruised.
Similar species: Common milkweed has similar shaped opposite leaves, but hemp dogbane leaves are much smaller and plants have many branches. Common milkweed stems are pubescent, whereas hemp dogbane are glabrous.
Miscellaneous: Fibers from the stems were used to make rope and clothing. The milky sap contains toxins that deter feeding by herbivores. Milkweeds are now in the dogbane family, but monarchs are unable to utilize hemp dogbane as a food source for larvae.
Meaghan Anderson Field Agronomist in Central Iowa
Meaghan Anderson is a field agronomist in central Iowa and an extension field specialist at Iowa State University Extension and Outreach. Educational programming is available for farmers, agribusinesses, pesticide applicators, certified crop advisors, and other individuals interested in...