Black Henbane (Hyoscyamus niger L.)
Black henbane is an annual or biennial forb that grows from a stout taproot. In its first year, it forms a basal rosette of leaves. During the second year, it produces an upright flowering stem typically reaching about 3 feet tall, though it may grow as tall as 6 feet under favorable conditions.
Stems and leaves are gray-green and densely covered with sticky, greasy hairs that emit a strong, unpleasant (“fetid”) odor when crushed. Leaves are large—2 to 8 inches long and up to 6 inches wide—with shallow lobes or toothed margins and prominent pale mid-veins.
Flowering occurs from mid-spring through late summer. Flowers are borne on racemes and are large and showy, up to 2 inches across. Each flower is funnel-shaped with five lobes fused at the base. Petals range from pale cream or yellowish-green to brownish-yellow and are heavily veined with purple. The center of the flower is often deep purple to nearly black, giving the plant its common name.
The calyx forms a distinctive, urn-shaped capsule about 1 inch long. At maturity, a thickened lid pops off, releasing numerous small black seeds. The woody flower stalks and skeletal seed capsules often persist long after the rest of the plant has died, making mature plants easy to identify.
Black henbane contains the toxic tropane alkaloids hyoscyamine, scopolamine, and atropine in all plant parts. Although historically used medicinally, these compounds can be highly toxic—and potentially fatal—to humans, livestock, and wildlife. Alkaloids may also be absorbed through the skin, so care should be taken when handling the plant.
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highly toxic—and potentially fatal—to humans, livestock, and wildlife
Quick ID
GuideLife Cycle:
• Annual or biennial
• Taproot
• Basal rosette first year
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Height:
• Typically 3 feet (up to 6 feet)
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Leaves:
• Gray-green with white mid-vein
• 2–8 inches long
• Lobed or toothed margins
• Sticky, hairy, foul-smelling
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Flowers (Mid-Spring–Late Summer):
• Up to 2 inches wide
• Funnel-shaped, 5 lobes
• Cream to yellow with purple veins
• Dark purple to black center
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Seeds/Fruit:
• Urn-shaped capsule (~1 inch)
• Lid pops off at maturity
• Numerous small black seeds
• Woody “skeleton” stems persist
Management Options
Prevention and cultural control practices should be emphasized whenever possible.
Because black henbane develops from a taproot, it can often be effectively controlled by hand pulling or digging, provided the entire root is removed. Tilling or hoeing can also be successful if the taproot is severed at least 2 inches below the soil surface. Controlled grazing is not recommended due to the risk of livestock poisoning. Mowing or chopping will not eliminate infestations, but may help reduce seed production if conducted before seeds mature. Do not mow once seed capsules are present.
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Larger infestations can be managed with herbicides. Spring and fall applications targeting rosettes are most effective, though treatments applied to bolting plants can also provide control. Flowering plants may be cut, and the remaining rosette or regrowth treated with herbicide to prevent reflowering. Always read and follow the herbicide label before application. Contact Sublette County Weed & Pest for assistance with product selection, rates, and application guidance.
