Flower:

Small clusters of stalked flowers scattered along branching stems (not always at a leaf node), the flower stalks all mostly attached at the same point (umbellate), at the tip of the cluster's stalk. Flowers are ¼ to 1/3 inch across, star-shaped with 5 petals fused at the base, usually white, sometimes violet, and typically green at the base. Petals are spreading or curled back. In the center is a column of 5 yellow stamens surrounding a green style just visible at the tip of the column. The calyx is star-shaped with 5 triangular lobes and sparsely short-hairy.

Leaves and stems:

Leaves are thin, alternate, 1 to 3 inches long, up to 2 inches wide, generally egg-shaped, pointed at the tip, rounded or wedge-shaped at the base, on a winged stalk. Edges are often wavy, and toothless or with a few large, blunt teeth. Surfaces are mostly sparsely hairy, more densely so on major veins on the underside.

The lower leaf surface may be light green or purple tinged. Stems are heavily branched, round to somewhat angled, hairless or sparsely hairy, and erect to sprawling.

Fruit:

Fruit is a ¼ to 1/3-inch round berry that ripens to shiny black.

Notes:

This native, weedy species was once listed as a county-level noxious weed and is part of the “Black Nightshade complex”, a group of related plants with very similar characteristics. The three species of concern here are: Solanum americanum, Solanum nigrum and Solanum ptychanthum. Some references treat these as synonyms of the same species, others as separate species, some as native, others as introduced or adventive. The DNR lists the species present in MN as S. nigrum var. virginicum, but we are following Michigan Flora's lead on this one and calling it S. ptychanthum. S. nigrum is more consistently considered a European introduction that is mostly present on the North American east and west coasts; its flower clusters are a more typical raceme (not umbellate) and flowers have a very small calyx, most noticeable on the fruit. S. americanum is a more southern native species whose unripe berries are speckled white, and does not have any purple tinged leaves. We don't believe the purple tinged leaves are a reliable trait in the field, however, since we had some difficulty finding any images showing this characteristic—nearly all of our own leaf images showed a green underside. Overall, Black Nightshade is also very similar to Hairy Nightshade (S. physalifolium), which is, as the common name suggests, densely hairy all over where Black Nightshade is sparsely hairy at best.