This species is known also as wild cotton, rheumatism-root, amy-root.
The flowers of this species differ from the above in being greenish-white, without perfume. The corolla lobes are ascending and not longer than the calyx lobes. The seeds are slightly longer. The black Indian hemp has a strong, tough fibre, at the same time fine and soft, which is used by the North American Indians in making bags, baskets, belts, fishing lines and nets. Both species are generally distributed across the continent, but are seldom found in close proximity.
Both the spreading dogbane and the black Indian hemp are said to be poisonous to live stock. As a rule the plants are not enticing to stock as they have tough stems, but in the early summer, when the stalks are tender and succulent and in those places where the plant is abundant and more wholesome vegetation is lacking, animals are tempted to eat the young green shoots.
The black Indian hemp contains the poisonous glucoside apocynin, as well as the glucoside apocynein.