It grows to a height of 10-30 cm from a creeping rhizome, with narrow, triangular leaves 7-15 mm across. The flowers are produced in late spring to early summer, 10-15 mm diameter, pale bluish or yellowish-white with a short, greenish or yellowish spur. The petals are rounded and broad in relation to their width.
In the British Isles, it is rare, confined to eastern and northern England and damp hollows with limestone soils in western Ireland. Efforts are being made to re-introduce it to newly suitable habitat in The Fens as part of the Great Fen Project.