Genus: 18 species.
Region: cool temperate to subarctic regions of Asia, China 16 species,Europe 2 species, North America 1 species.
BotanyAnnual or perennial plants, ± 10 cm tall.
Leaves: basal rosette; 2 to 3 cm long; secondary whorls of smaller leaves on the flower stems.
Flowers: 5 white to pale blue petals, joined at the base; 2 cm across.