Toxic Parts:
all parts, leaves
cyanogenic glycosides
Flower Color:
  • flower color
waterside, meadows, wetlands

Time of Greatest Risk


Geographical Distribution

Hemp dogbane distribution - United States

Related Species

Hemp Dogbane

Apocynum cannabinum

Common Dogbane, Indian Hemp
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Hemp dogbane (Apocynum cannabinum) is a herbaceous perennial plant from the dogbane and milkweed family. It is native to the Northeastern United States and Canada, however it is found throughout the United States. Hemp dogbane is considered to be a weedy plant and has an underground root system that allows it to spread rapidly. The plant got it's name from when native Americans use to use its strong silky fibers from the stems, used to make netting, rope, and other materials. The plant begins growing in late spring or early summer.

Hemp Dogbane Toxic Components

Hemp dogbane contains cyanogenic glycosides, which are toxic to horses if ingested. The plant's primary toxin is cymarin, which was once used as a heart stimulant for humans. Normally, horses avoid hemp dogbane because of its bitter, sticky, milk-white juice. Horses that are poisoned from this plant usually die within 6 to 12 hours after eating the plant. Both dried and green plants are toxic. Cases of poisoning are more likely to occur if horses are turned out in fields containing the plant but provided no alternative food to eat.

What Hemp Dogbane Looks Like

  • Height: Grows to 1 to 2 meters tall.
  • Flowers: Panicles of small, white, flat-headed to dome-shaped, 5-petaled flowers spanning 1 to 3 inches in diameter terminate from the upper stems and some lateral stems. The flower petals are ovate to oval in shape and have a sweet fragrant. It's flowers bloom from July to August.
  • Stems: Light green to red, terete, glabrous, and sometimes glaucous; contain a milky latex.
  • Leaves: Pairs of opposite leaves that are 1 to 3 inches in length develop along the stems. Each leaf is broadly elliptic to broadly elliptic-oblong in shape, with smooth margins. The upper portion of the leaves are medium green initially, and turn yellow in the fall.
  • Fruits: 4 to 8 in long, narrowly cyclindrically-shaped, dark brown follicles (seedpods that open along one side) develop which will eventually split open to release the numerous seeds into the wind.
  • Roots: It has a long-rhizomatous root system, allowing it to spread aggressively in moist open areas.