Indian hemp, or prairie dogbane, is a shrubby, upright perennial with opposite branches and milky sap. The stems are reddish and often grow higher than the flower cluster.
The flowers are tiny, 5-pointed bells, massed in clusters (cymes), white or greenish white, and attractive to bees.
Blooms June–August.
The leaves are opposite, smooth-edged, variable, oblong or lance-shaped, hairy or not hairy, with conspicuous petioles (stalks).
Similar species: Spreading dogbane, or pink-flowered dogbane (Apocynum androsaemifolium), has larger flowers in looser (less dense) clusters. Its flowers are pink or white with red inside, and the petal lobes spread. The leaves tend to droop or spread. It is scattered mostly south of the Missouri River.
- Missouri's two dogbanes live in the same habitats and can produce hybrids that can make identifications tricky.
Height: to 3–4 feet.
Statewide.
Habitat and Conservation
Occurs in prairies, glades, forest openings, bottomland forests, margins of swamps, ponds and lakes, banks of streams and rivers, pastures, ditches, levees, roadways, waste places, and other open, disturbed areas.
Status
Native Missouri wildflower.
Human Connections
Dogbane stems have a tough, fibrous bark that can be used like hemp for making rope, nets, straps, and so on. Native Americans were using it for cordage thousands of years ago. People still use it for making rope and twine, and fabric for clothing.
When bruised, all parts of the plant exude a toxic white juice; the plant has a long list of folkloric medicinal uses.
The milky latex sap can potentially be used for making rubber.
Ecosystem Connections
Curiously, most dogbane plants produce few seeds, even though insects avidly visit the flowers. Apparently these plants must be cross-pollinated, but insects don't seem to accomplish this. Most populations consist of one or a few large clones (genetically identical individuals), which develop from the spreading roots.
The toxic juices make this plant inedible to most mammals, but several types of moths eat this plant as caterpillars. They build up the toxin in their bodies and become unpalatable to predators.
- The delicate cycnia (Cycnia tenera), a type of tiger moth, is found wherever dogbane grows in Missouri.
- Dogbane is also is a larval food plant for the snowberry and hummingbird clearwings, sphinx moths that mimic hummingbirds.
Dogbanes (family Apocynaceae) used to be separated from the milkweeds, which used to have their own family (Asclepiadaceae). The two have now been combined. The dogbanes' name (Apocynaceae) was older, so it became the name for both.
Botanists have long known the dogbane and milkweed families were closely related. In about 2000, they announced that DNA evidence showed they were so close genetically that calling them separate families was not warranted. But the two groups do have distinctively separate floral structures, and the milkweeds are considered a unique subfamily or tribe of the dogbane family.
