Apocynum cannabinum - Indian Hemp / Hemp Dogbane

Taxonomy & Identification

Feature	Detail
Family	Apocynaceae
Common names	Indian hemp, hemp dogbane, prairie dogbane, Amy root, rheumatism root, wild cotton
Life cycle	Perennial herbaceous
USDA hardiness	Zones 4-8
Native range	Throughout North America - all 48 US states and much of Canada

The plant grows 2-5 feet tall with opposite, oval leaves. All parts exude a milky white latex sap when bruised. Small, greenish-white tubular flowers appear in clusters, followed by long, slender paired seed pods. The stems contain high-quality bast fibers.

Phytochemistry

The primary active compounds are cardiac glycosides, chiefly:

Cymarin - the principal toxin, once used therapeutically as a heart stimulant; its potency levels in the plant are disputed across the literature
Apocynamarin - structurally related glycoside
Resins and latex compounds (cause contact dermatitis)

These glycosides act similarly to digitoxin, inhibiting the Na+/K+-ATPase pump in cardiac muscle cells.

Toxicity

All parts - leaves, stems, roots, flowers, fruits, seeds - are highly toxic, both green and dried.

Signs and symptoms of poisoning:

Rapid or irregular pulse / cardiac arrhythmia
Nausea, vomiting, diarrhea
Pupil dilation
Progressive muscle weakness
Cyanosis of mucous membranes
Convulsions, coma, death
Contact with milky stem sap: skin blistering / dermatitis

Susceptible animals: humans, dogs, cats, horses, cattle, sheep. Lethal dose for livestock is approximately 0.5 g/kg body weight; as little as 15 g of green leaves has reportedly killed cattle.

Death from ingestion typically occurs within 6-12 hours.

Treatment follows the digitoxin toxicosis protocol: activated charcoal, emetics (in species that can safely vomit), atropine for bradycardia, electrolyte correction. Antidigitalis antibody fragments (Digibind/FAB) may be useful, though binding affinity to Apocynum glycosides specifically is not firmly established.

Ecological Role

Larval host for the snowberry clearwing moth (Hemaris diffinis), the dogbane tiger moth (Cycnia tenera), and the zebra caterpillar (Melanchra picta) - these Lepidoptera have evolved tolerance to the cardiac glycosides
Nectar source for bees, butterflies, and other pollinators; produces an almost colorless, high-quality honey
Stems used for nesting by solitary/stem-nesting bees
Tends to increase on grazed pastures (livestock avoidance) - considered a weed in cultivated land

Historical & Ethnobotanical Uses

Fiber: Indigenous peoples across North America used the strong bast fibers from the stem bark to make rope, twine, thread, netting, bags, and clothing. This is the origin of "cannabinum" (hemp-like) in its name, though it is entirely unrelated to Cannabis.

Medicinal (traditional): Used by many Native American tribes for:

Rheumatism
Coughs, whooping cough, asthma
Smallpox / pox
Internal parasites (vermifuge)
Diarrhea
Increasing lactation

The root - harvested in autumn and dried - was used as a cardiotonic, diaphoretic, diuretic, emetic, and expectorant. Weak root tea was used for cardiac disease and as a febrifuge.

Important caveat: Due to its narrow therapeutic window and high toxicity, internal use should only occur under qualified medical supervision. It is not used in mainstream modern medicine.

Other Uses

Hydrocarbon potential: Research has explored A. cannabinum as a hydrocarbon-producing crop for bioenergy
Gum substitute: Dried milky latex from stems was historically chewed as a gum substitute
Honey production: Flowers yield a superior, nearly colorless honey

Key Distinction

Despite its common name "Indian hemp" and the species epithet cannabinum, this plant has no relationship to Cannabis sativa. The name refers only to its fiber-producing properties. It contains no cannabinoids and is taxonomically placed in Apocynaceae, not Cannabaceae.

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