Black nightshade (Solanum nigrum)
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Black nightshade is a summer annual or short-lived perennial broadleaf. In California, it is found in the North Coast, northern Central Coast, San Francisco Bay region, Central Valley, southern coastal California, western Transverse and Peninsular Ranges, up to 660 feet (200 m) and inhabits agricultural land and other disturbed areas. Black nightshade is a member of a complex of closely related species that can be highly variable, making identification difficult.
Black nightshade is one of the most problematic of the nightshades. They, and other nightshade species, can harbor diseases and pests that affect closely related crops such as tomatoes, potatoes, and peppers. Some nightshade biotypes have developed herbicide resistance. Mature plants can form a sticky mass that clogs harvesting machinery. Nightshades contain several glycoalkaloid compounds that can be toxic to humans and livestock when ingested. However, the degree of toxicity depends on many factors, including plant maturity and environmental conditions.
Orchards, vineyards, crop fields, pastures, gardens, yards, fields, roadsides and other disturbed, unmanaged sites.
Cotyledons (seed leaves) are narrowly egg shaped to lance shaped, covered with tiny hairs, and about 1/6 to 2/5 of an inch (4–10 mm) long. The stalk below the cotyledons is usually covered with short to long glandular hairs. The first true leaves are spade shaped with smooth edges and the lower surface is often purple. Later leaves are increasingly larger, egg shaped, dark green, often purple tinged, with a smooth to slighly wavy edge, and covered with short nonglandular hairs and some glandular hairs. Hairy nightshade is similar and has glandular hairs.
Mature plants are erect to bushy and vary greatly in form and color. Stems, leaves, and leaf stalks have some hairs but are not densely hairy or sticky. The related hairy nightshade plant, however, is conspicuously covered with glandular hairs and is sticky to the touch. Although black nightshade leaves vary, they are overall egg shaped with a smooth to wavy edge or an irregular, shallow-toothed edge, and they are alternate to one another along the stem. Stems of perennial black nightshade plants sometimes become slightly woody at the base.
Flowers bloom from March through October. Four to eight star-shaped, usually white flowers grow in a cluster. Another species, silverleaf nightshade, S. elaeagnifolium, has colorful showy flowers.
Berries turn from green to black when mature and the outer portions of the flower cover only a small part of the fruit surface, and sometimes curl away from the fruit. Mature berries are dull, black or purplish black, and range from about 1/5 to 3/10 of an inch (5–8 mm) in diameter. Silverleaf nightshade has yellow to orange berries. Mature hairy nightshade berries are green or yellowish brown when mature, never black.
Seeds are egg shaped, flattened, pitted on the surface, and 1/5 to 1/3 of an inch (5–8 mm) in diameter.
Reproduces by seed.
Related or similar plants
- American black nightshade, Solanum americanum
- Hairy nightshade, Solanum physalifolium
- Horsenettle, Solanum carolinense
- Silverleaf nightshade, Solanum elaeagnifolium