Solanum nigrum (Black Nightshade)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Solanales
Family: Solanaceae
Genus: Solanum
Species: S. nigrum
Scientific name: Solanum nigrum

Common name: Black nightshade, Garden Nightshade.

This plant is poisonous. Though some literature suggests that ripe berries are not poisonous, the toxicity of Solanum nigrum varies widely depending on the variety, and poisonous plant experts advise to avoid eating the berries unless they are a known edible strain. The toxins are most concentrated in the unripe green berries, but also occur in ripe berries. Death from ingesting plant parts results from cardiac arrhythmias and respiratory failure. Children have died after eating unripe berries.

Black nightshade is an annual to short-lived perennial plant that has white or mauve flowers followed by berries that are first green, but change to black as they ripen. Mature plants can grow up to 75cm tall and flower between October and May. Well established plants become "bushy" as the main stem develops laterals. Leaves are pointed at the tip; expand in the middle and narrowing back to the leaf stalk. Leaf margins have a toothed appearance. Black nightshade is found in arable land, disturbed pasture, gardens and waste areas throughout New Zealand, but is less abundant in the lower South Island.
This is the plant most people mistakenly call deadly nightshade. The true deadly nightshade (Atropa bella-donna) can live up to its common name, but is fortunately very rare and only recorded in Christchurch, this species is considered poisonous to humans. Black nightshade is a problem in pea crops when the green berries are mistaken for peas during harvesting. The berries produced by black nightshade are often eaten by birds, and the seeds are thus spread in bird droppings.
Not to be confused with Deadly Nightshade, which has large bell-shaped, brownish-purple flowers, as opposed to the white star-like flowers of Black Nightshade. And the glossy black berries on Deadly Nightshade can be twice the size of those of Black Nightshade.