Lycianthes rantonnetii, the blue potato bush or Paraguay nightshade is a species of flowering plant in the nightshade family Solanaceae, native to South America.It Grows to about 6 ft (1.8 m) tall and broad, it is a rounded evergreen shrub with a somewhat lax habit. A profusion of trumpet-shaped, bright blue-purple flowers with a prominent yellow eye appear in summer, followed by red berries. It requires a sheltered location in full sun.Though related to food plants like the potato and tomato, all parts of the plant are considered toxic to humans.