[1] Growing to 1 m (3.3 ft) tall and broad, this hardy herbaceous perennial has a basal rosette of toothed leaves.

Large, showy, pure blue flowers with a prominent yellow central boss are produced in late Spring.

The plant is valued as an ornamental, but is notably difficult to grow in normal garden conditions.

It prefers an evenly cool temperature and shaded conditions, in somewhat acid soil which remains reliably moist.

[2] The following cultivars are recipients of the Royal Horticultural Society's Award of Garden Merit: