Common Dogbane (Apocynum cannabinum), also known as Indian Hemp, is a perennial herb superficially similar in looks to Milkweed. It is recognized by clusters of small, bell-shaped white to pink flowers, milky sap (seen when the stem is broken) and long seed pods.
Plants usually grow two feet to three feet in height, but they can reach five feet at maturity. Initially, in late spring, this plant begins its growth as an erect central reddish stem with opposite oval leaves. By mid-summer, it branches abundantly. The stems are smooth and rounded. At intervals along the stems are pairs of opposite leaves, two inches to three inches long and about one-third as much across. They are oval in shape and smooth along their edges. The upper leaf surface is blue green and smooth, while the lower leaf surface is lighter in color, also smooth.
Upper stems and some lateral stems end in the clusters of tubular shaped flowers. These clusters can measure from one inch to three inches across. The blooming period usually occurs throughout the summer. An individual plant blooms for about a month.
The flowers are sweetly fragrant. Cross-pollinated flowers eventually produce pairs of narrowly cylindrical seedpods that open along one side and are four inches to eight inches in length. At first, they look like green bean pods but turn brown when mature. They eventually split open and release their seeds to the wind. Individual seeds are linear and about one-quarter inch long with tufts of white hair at either end. These hairs catch the wind, which carries them to a new location.
The root system is also far spreading, often producing whole colonies of new plants. Habitats include a variety of moist areas, from bogs and swamps to the margins of streams and rivers. It is a pioneer species of poorly drained fields and vacant lots.
The name ‘Indian Hemp’ is also used for this plant because native Americans obtained strong silky fibers from the stems. These fibers were used as twine in basketry, mats, netting, rope and other artifacts. Some early French explorers remarked upon the abundance of this plant in the original prairie, which they referred to as ‘hemp’ in their writings.
Even though Dogbane is somewhat poisonous to humans, dogs and grazing animals, it is usually not fatal. However, contact with the milky sap can cause a rash.
Dogbane has also been used medicinally in the past. The tea from boiled seeds or roots were used to provide a reaction similar to that of Digitalis – to regulate heartbeat, and for dropsy or kidney failure. However, ingestion of the milky sap can definitely irritate the intestines. Dried and pulverized roots were used for colds and coughs, headache and congestion. It was also used to treat convulsions. A small section of root was liquified by mashing and heating it. The liquid was then taken internally or applied to the skin.
Although Dogbane is a potential poison to a variety of mammals, it is a particular favorite of insects and butterflies.