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 charming little bog plant with rounded leaves and white flowers. There are several North American species and nubicola from the Himalayas, all very similar in appearance. They like damp peaty soil, and are increased by division and from seeds.