Common Nightshade Solanum americanum

American black nightshade is an annual or short-lived perennial. Its growth habit is erect as an herbaceous plant or small shrub. The plant may reach a height of 4 feet tall. Star-shaped white flowers with a yellow cone-shaped center are present in the summer and fall. The green fruits mature into shiny black berries. The leaves and berries are toxic to livestock and humans. It is a member of the Solanaceae or nightshade family that also includes tomatoes, potatoes, eggplants, and peppers.

American black nightshade is native to North and South America. This species is the most widespread throughout the world of the Solanaceae or nightshade family. They usually appear as a weed in the forest, thickets, grasslands, mountain slopes, wastelands, and cultivated gardens or crop fields. It is found in tropical and sub-tropical areas also.

The genus name, Solanum, is the Latin word, solamen, which means "comforting or soothing." The species name, americanum, is Latin for "from America." Some botanists consider this to be more than one species while others think it is a subspecies. Reportedly, another scientific synonym of American nightshade is Solanum ptycanthum.

The plant prefers full sun and can tolerate partial shade. It will thrive in moist soils. It can easily escape cultivation and become a weed. This plant is not recommended for most gardens. It is pollinated by insects, bumblebees, and flies. It is easily propagated by the dispersal of seeds. 

American black nightshade has a fibrous root system and slender taproot. The stems are green and erect. The undersides of the green leaves are slightly hairy. The white star-shaped flowers and berries appear in clusters. 

Unfortunately, this species competes with vegetable crops and reduces the harvest. Its toxicity to livestock is a concern in pastures or hayfields. Manual control by hand weeding is the only option when vegetable crops are present. Using cover crops helps reduce seed germination and weed growth. 

American black nightshade contains a toxin known as solanine. All parts of the plant are potentially toxic to humans and all animals including pets if ingested. The leaves and berries are reportedly the most toxic. Ingestion of this plant can cause gastrointestinal problems, weakness, hallucinations, convulsions, and possible death.

Seasons of interest:

Bloom:  Summer and Fall    Fruits:   Summer and Fall

Quick ID Hints:

• stem green, erect, angular, and smooth or slightly hairy
• green to dark green ovate or lanceolate leaves, slightly hairy undersides
• flowers are clusters of umbel-like, star-shaped, five-petaled blooms with a yellow columnar center
• green fruits with white flecks that ripen to shiny black or blackish-purple berries

Insects, Diseases, and Other Plant Problems:  American nightshade is the host of many plant pests such as the Colorado potato beetle.  American black nightshade competes with vegetable crops and becomes weedy. It is reported as invasive in Hawaii's Haleakala National Park.

The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on common pests and diseases of eggplant.