This section is from the book "Commercial Gardening Vol2", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
A pretty Japanese perennial, 6 in. high, resembling Ramondia in appearance. It has lilac flowers with a bright-purple centre in summer, and likes a peaty soil. Increased by dividing and pegging down the rhizomes in spring.