This genus is named after French botanist Jacques Barrelier (1606-1673). I have not had much success with growing Barleria, except for this one, which was given to me as a cutting by a friend. This is a pretty, petite shrub, about 80 cm high, which is covered in simple, five-petalled, tubular flowers in autumn: they remind me of citrus blossoms. The blooming season is not long but the flowers are so profuse over the entire shrub that it is a joy to behold. The main species has purplish-blue flowers, and there is also a clear white version, my personal favourite. Another variety has a white flower mottled and striped with lavender. It grows is sun or part-shade - it may be too lanky if situated in a full-shade position. Prune it back quite hard after flowering is over. The species is found over a wide range of Eastern Asia, including Southern China, India, Myanmar, Thailand and Vietnam.
Postscript: In the end, I removed this plant. It was pretty when in bloom, but the flowering season seemed too short to justify the space it occupied for the rest of the year. I still enjoy seeing it in the gardens of my friends from time to time.