Virginia Tech Weed Identification Guide

Eastern Black Nightshade: Solanum ptycanthum

Weed Description:   An erect summer annual, reaching as much as 1 1/3 feet in height.  Eastern black nightshade is primarily a weed of agronomic crops, pastures, and hay fields that is found throughout the United States east of the Rocky Mountains.

Roots:  A taproot with a branched fibrous root system.

Seedlings:  Stems below the cotyledons (hypocotyls) are covered with small hairs and are green or sometimes tinted maroon. Cotyledons are green on the upper surface, purple- or maroon-tinted on the lower surface.
Leaves:  Young leaves remain purple- or maroon-tinted on the undersurface. Leaves are simple, alternate, ovate or ovate-lanceolate. Leaf margins may be entire or with blunt teeth. Leaf hairiness is variable, however leaves are most often found to be slightly hairy.

Stems:  Branching, round or angular, smooth or only partially hairy, and becoming woody with age.

Flowers:  Star-shaped (4-10 mm in diameter), white or purple-tinged, in umbel-like clusters of 5-7.

Fruit:  A berry, 5-12 mm in diameter, green when immature, turning purplish-black at maturity.  Berries contain 4-15 sclerotic granules.

Identifying Characteristics:  Cotyledons of young leaves are purple- or maroon-tinted on the undersurface. Emerging plants might be confused with Bittersweet Nightshade (Solanum dulcamara) seedlings, however most bittersweet nightshade plants spread via creeping stems that root at the nodes and do not have a purple- or maroon-tinted leaf undersurface.   Additionally, mature nightshade plants may be distinguished by berry color (eastern black nightshade: purplish-black; bittersweet nightshade: red).