H10 in. x W18 in. Upright stems with leaves similar to C. betulifolia end in rich, violet-purple bells. Native to the western Caucasus. Hardy to Zone 6.

These justly popular rockery plants have differing needs, but are always rewarding. Most spread readily with underground runners or creeping stems; others are saxatile alpines, best grown in deep grit with a gravel collar. In general, they prefer gritty, well-drained soil and full sun to partial shade.