Hailing from South America, this is a lax, rambling shrub, sometimes known as the blue potato bush. It flowers in the warmer months, having rounded violet-blue flowers, more intensely coloured in the cultivar 'Royal Robe'. It can grow up to 2.4 m tall and seems best when trained against a trellis or on an arbour, or when standardised to a single trunk. The shrub is best in a sunny, well-drained position. Propagation is by cuttings in summer and autumn. This plant belongs to the Solanaceae family of plants. Note that the correct name for this plant is now Lycianthes rantonnei.
Postscript: whilst I enjoyed the flowers on my standardised specimen of this shrub, I found it needed constant clipping to keep the rounded shape, and eventually it was taken out.