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Wisconsin Plant of the Week

Apocynum androsaemifolium L.

Apocynaceae (Dogbane Family)

Common Name:

spreading dogbane


Dogbane is a bushy native perennial, with reddish stems and clusters of small, nodding, bell-shaped flowers. It grows in dry open forests, prairies and disturbed sandy soil often associated with fire. Like plants in the closely related milkweed family, the dogbanes have a milky sap in their stems and leaves. The sap is poisonous to mammals and dries like rubber.

Flowers bloom from June through August and dangle from curved stalks.  In bud the flower petals look twisted. The five petals and 5 sepals are joined to form a cup with 5 recurved lobes. The petals are white to pale pink with pink strips inside. Another common name is “fly-trap”, since 5 scales inside the flower bend inward when touched and trap small insects.  The fragrant flowers attract ants, beetles, butterflies and hawk moths.

Fruit are red when ripe from August to October.  They’re narrow follicles in drooping pairs, up to 20 cm long. Like milkweeds they split open along one side and release seeds with a tuft of long, silky hairs.

Leaves either spread outward or droop. They’re opposite, oval, 4 to 6 cm long, toothless, dark green with prominent white veins above and pale below. 

The fibrous outer stem was used for thread, like that of a very similar plant, Indian hemp (A. cannabinum). Indian hemp lacks the pink stripes inside its flowers, its petals don’t curve backward, and its leaves point up.

  • Origin of the name: Apocynum, “dog bane” from apo, L. away from, and kunos, Gk., dog.  The species epithet contributes to the bad reputation of scientific names: androsaemifolium, from androsaimon, Gk., man’s blood, which refers to the blood red juice of another unrelated plant, and folius, L., leaf.  Thus “the plant whose leaves resemble the plant named for its juice which is the color of human blood” -- even though dogbane sap is white.
  • Range:  N. Amer., s. to TX, GA, only at higher altitudes further south
  • WI Range:  Statewide
  • Common associates: oak, pine, aspen, fireweed, bracken fern
  • Wetland Indicator Status: [UPL]
  • Coefficient of Conservatism: 2, WI; 3, MI; 5, Chicago Region
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