Two types of nightshade are widespread across parts of the United States. Nightshade is a plant that has berries and leaves containing a toxin known as solanine. When ingested in large quantities, solanine has the potential to be deadly. Specific features of these two nightshade species allow you to make an accurate identification of the plants.
The "National Audubon Society Field Guide to Wildflowers" notes that common nightshade can grow to heights between 1 foot and 2 1/2 feet. Climbing nightshade, another abundant type of nightshade that goes by the name of bittersweet nightshade in some regions, takes the form of a vine, capable of producing stems as long as 8 feet.
Common nightshade's leaves are variable in length, growing from 2 to 4 inches long and owning an oval shape. The leaves of common nightshade have pointed ends and the margins, or edges of the leaf, are wavy. Climbing nightshade possesses leaves that can be 3 1/2 inches long. Their forms may be heart-shaped or oval and the leaves grow in an alternate pattern along the stems, with just a single leaf at each node. The colors of the leaves of both species are a dark shade of green.
Common nightshade flowers are white, while that of the climbing nightshade plant is a lavender or bluish hue. Both flowers feature a drooping star shape, with the petals peeling backwards away from the face of the flower, which contains a yellow cone of anthers. The flowers will grow in clusters along the stems and they are barely a half-inch wide in climbing nightshade, with those of common nightshade being only slightly larger. Climbing nightshade produces flowers from May through September. Common nightshade's flowers bloom from June right through November in many parts of the plant's range.
The fruit of nightshade is at its most toxic when it is immature and not ripened. Once it has developed fully, the fruit is much less dangerous to consume, although it is prudent not to eat it. The berry that a common nightshade plant produces is green, but in time turns a deep black color. The fruit of climbing nightshade goes from its original green tint to a bright red, hanging in clusters like small tomatoes; indeed these nightshade plants belong to the same family, Solanaceae, as tomatoes and potatoes do.
You will find climbing nightshade in clearings, open woodlands, thickets and alongside rivers and stream, states the Montana Plant Life website. This plant can grow in partial shade. Common nightshade occurs in both thickets and clearing, emerging often in disturbed soils and in cultivated fields.