Solanum

Solanum, the nightshades, horsenettles and relatives, are a large and diverse genus of annual and perennial plants. They grow as forbs, vines, subshrubs, shrubs, and small trees, and often have attractive fruit and flowers. Many formerly independent genera like Lycopersicon (the tomatoes) or Cyphomandra are included in Solanum as subgenera or sections today. Thus, the genus nowadays contains roughly 1,500-2,000 species. The species usually most commonly called nightshade in North America and England is Solanum dulcamara, also called bittersweet and woody nightshade. Its foliage and egg-shaped red berries are poisonous, the active principle being solanine, which can cause convulsions and death if taken in large doses. The black nightshade (S. nigrum) is also generally considered poisonous, but its fully ripened fruit and foliage are cooked and eaten in some areas.

The generic name was first used by Pliny the Elder (23-79) for a plant also known as strychnos, most likely S. nigrum. Its derivation is uncertain, possibly stemming from the Latin word sol, meaning "sun," referring to its status as a plant of the sun. Another possibility is that the root was solare, meaning "to soothe," or solamen, meaning "a comfort," which would refer to the soothing effects of the plant upon ingestion.

Most parts of the plants, especially the green parts and unripe fruit, are poisonous to humans (although not necessarily to other animals), but many species in the genus bear some edible parts, such as fruits, leaves, or tubers. Several species are cultivated, including three globally important food crops:

• Tomato, S. lycopersicum
• Potato, S. tuberosum
• Eggplant, S. melongena

Other species are significant food crops regionally, such as Ethiopian Eggplant and gilo (S. aethiopicum), naranjilla or lulo (S. quitoense), Turkey Berry (S. torvum), pepino (S. muricatum), or the "bush tomatoes" (several Australian species).

While most medical relevance of Solanum is due to poisonings which are not uncommon and may be fatal, several species are locally used in folk medicine, particularly by native peoples who have long employed them. Giant Devil's-fig (S. chrysotrichum) has been shown to be an effective treatment for seborrhoeic dermatitis in a scientific study.

Solanum species are used as food plants by the larvae of some Lepidoptera species (butterflies and moths) - see list of Lepidoptera that feed on Solanum.