Black henbane (Hyoscyamus niger)

Synonyms: Hyoscyamus vulgaris, Hyoscyamus agrestis, Hyoscyamus auriculatus

Common Names: Henbane, stinking nightshade, hog's bean, fetid nightshade

Description:

Black henbane (Hyoscyamus niger) is a coarse, foul-smelling, sticky-hairy plant in the nightshade family, native to Europe, western Asia, and North Africa [1]. It was brought to North America as a medicinal and ornamental herb and now grows wild as an invasive weed across the Northeast, Midwest, and West, mostly in disturbed and overgrazed ground [2][4]. MISIN tracks it because it spreads fast by seed and ? more importantly ? because every part of the plant is highly poisonous to people, pets, and livestock [2][3].

Habit:

Black henbane is a stout, branching plant 1 to 3 feet tall, covered in sticky hairs and giving off a strong, unpleasant smell [2]. Its leaves are large ? up to about 8 inches long ? coarsely toothed or shallowly lobed, and grayish-green [2]. From late spring into early fall it bears distinctive funnel-shaped flowers about 1 to 2 inches across: dull creamy to greenish-yellow, laced with dark purple veins, with a deep purple throat [2]. As the flowers fade, they leave rows of urn- or pineapple-shaped seed capsules along the stem, each packed with seeds [2]. It is easiest to spot in summer, when it is in flower and the strange purple-veined blooms and foul smell make it hard to mistake [2].

At-a-glance cues:

1. Coarse, sticky-hairy plant 1 to 3 feet tall with a strong, foul smell [2]
2. Funnel-shaped creamy-to-greenish-yellow flowers with dark purple veins and a deep purple throat [2]
3. Large, grayish-green, coarsely toothed or lobed leaves up to about 8 inches long [2]
4. Rows of urn- or pineapple-shaped seed capsules along the stem [2]

Leaves:

1. Arrangement: alternate along the stem [1]
2. Shape: large and oblong, coarsely toothed to shallowly lobed [2]
3. Size: up to about 8 inches (20 cm) long [2]
4. Surface: grayish-green, covered in sticky hairs, and foul-smelling [2]

Stems:

1. Habit: erect, stout, branching annual or biennial, 1 to 3 feet (0.3 to 1 m) tall [2]
2. Surface: covered in sticky (glandular) hairs, with a strong unpleasant odor [2]
3. Biennial plants form a low leafy rosette the first year, then bolt and flower the second [2]

Flowers:

1. Color: dull creamy to greenish-yellow, with dark purple veins and a deep purple throat [2]
2. Shape: funnel-shaped, five-lobed, about 1 to 2 inches across [2]
3. Arrangement: in leafy, one-sided coils along the upper stem [2]
4. Bloom time: late spring into early fall (about May through September) [2]

Fruit and seeds:

1. Fruit: an urn- or pineapple-shaped capsule that opens by a lid when ripe [2]
2. Arrangement: in rows along the upper stalk [2]
3. Seeds: many and small ? a single plant can produce from tens of thousands up to about half a million [2]
4. Reproduction is by seed only; seeds spread in soil, hay, and water, and on animals and equipment [2]

Habitat:

Black henbane is native to Europe, western Asia, and North Africa [1]. In North America it is introduced and now grows wild across the Northeast, the Midwest, and much of the West [2][4]. It favors open, sunny, disturbed ground with well-drained or sandy soil: pastures, rangeland, roadsides, fence lines, waste areas, old fields, and overgrazed or trampled spots [2]. It is most common where the ground has been disturbed and there is little competition [2].

Reproduction:

Black henbane spreads only by seed, but it makes a great many ? a single plant can produce from tens of thousands up to about half a million seeds, which drop from the capsules and build up in the soil [2]. The seeds move in soil and water, in hay, and on animals, vehicles, and equipment, so it often turns up along roads, trails, and field edges [2]. Plants may behave as an annual (sprouting, flowering, and dying in one year) or a biennial (a leafy rosette the first year, then flowering the second) [2].

It flowers and sets seed from late spring into fall [2]. For control timing: dig or pull plants and cut off the flowering stalks before the seed capsules ripen in summer, so they cannot reseed [2].

Impact and Damage:

Black henbane is highly poisonous. Every part of the plant ? especially the seeds ? contains tropane alkaloids (atropine, hyoscyamine, and scopolamine) that can poison people, pets, and livestock [2][3]. Even small amounts can cause anticholinergic poisoning: dilated pupils, rapid heartbeat, dry mouth, confusion, hallucinations, agitation, convulsions, and, in serious cases, coma; in one report, as few as four flowers were enough to sicken a small child [3]. The sticky hairs can also irritate bare skin, so keep children, pets, and livestock away from it and wear gloves when handling it [2][3].

Livestock usually avoid its foul taste, but animals that do eat it can be poisoned, and it can contaminate pastures and hay [2][3]. In natural and working lands it invades disturbed ground, rangeland, and pastures, where it competes with desirable plants and its dense growth and persistent litter can keep other plants from establishing [2].

Similar species:

No commonly confused species in the MISIN region.

Monitoring and rapid response:

Signs to watch for:

1. A coarse, sticky, foul-smelling plant 1 to 3 feet tall on disturbed or overgrazed ground [2]
2. Funnel-shaped greenish-yellow flowers with dark purple veins and a purple throat, late spring into fall [2]
3. Rows of urn- or pineapple-shaped seed capsules along the stem [2]

What you can do:

1. Wear gloves and long sleeves ? all parts are poisonous and the sticky hairs can irritate skin; keep children and pets away [2][3]
2. Dig or pull plants, removing the taproot, when the soil is moist and before the seed capsules ripen [2]
3. Cut off and bag the flowering or seeding stalks before the capsules open, to stop the seed [2]
4. Bag and trash all plant parts rather than composting them, since the seeds last for years in the soil [2]
5. Keep ground cover healthy and avoid overgrazing ? black henbane needs bare, disturbed ground to get started [2]
6. Land managers can target outlying plants and dig or cut patches before seed set, repeating over several years to draw down the seed bank [2]

When to call a professional:

1. Large infestations across pasture or rangeland where hand methods cannot keep up, especially where livestock or children are at risk [2]
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Plants of the World Online (POWO), Royal Botanic Gardens, Kew. Hyoscyamus niger L. powo.science.kew.org
2. Utah State University Extension, Range Plants of Utah. Black Henbane (Hyoscyamus niger). extension.usu.edu
3. Alizadeh A, Moshiri M, Alizadeh J, Balali-Mood M (2014). "Black henbane and its toxicity ? a descriptive review." Avicenna Journal of Phytomedicine 4(5):297?311. pmc.ncbi.nlm.nih.gov
4. USDA NRCS PLANTS Database. Hyoscyamus niger L. plants.usda.gov

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