Corydalis fumariifolia

Corydalis fumariifolia Maxim. has light blue or indigo flowers, rarely purple or white, with the inner petals nearly white. It is native to light woodland and open stony ground in China, Korea, and Russia. Photographs by John Lonsdale.

The photo below is from Judy Glattstein who wondered about its identity. In her garden it is reliable, increasing slowly. It was identified as this species.