Idaho OnePlan recommends the website of the Idaho Weed Awareness Campaign as the best resource for up-to-date information about Idaho's noxious weeds, and their control.
Source for this page: Idaho's Noxious Weeds by Robert H. Callihan & Timothy W. Miller


Black henbane (Hyoscyamus niger) is a Mediterranean native that was introduced as an ornamental and medicinal plant in the 17th century. It spreads by seeds and is found in a variety or environmental conditions. Black henbane is narcotic and poisonous to humans. Livestock avoid it unless other forage is not available. Two alkaloids in black henbane tissues (hyoscyamine and scopolamine) are useful sedative/ anti-spasmodic drugs when used under controlled conditions.

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Black henbane is an annualPlant that germinates, flowers, seeds, and dies during one growing season or biennialPlant that germinates in one growing season, then flowers, seeds, and dies during a second plant that grows up to 3 feet tall. The entire plant is covered with greasy hairs. Leaves are up to 8 inches long and 6 inches wide, shallowly lobedA cut into a leaf from the edge toward the center; greater than toothed, but not quite compound, and heavy scented. Flowers are borne on spikesA narrow, nonspreading inflorescence form the leaf axils from May until September. They are showy, 5 lobed, up to 2 inches across, and greenish-yellow in color with deep purple veins and throats. The calyxThe outermost flower leaves (sepals) together, often green in color forms a 1-inch, urn-shaped "fruit" that has a thickened lid that pops off at maturity and spills the black seeds.


Black henbane is found in the northern U.S. and southern Canada.


No biological control agents are available for control of black henbane, but herbicides can provide excellent control.