Dutchman's breeches

noun[plural only]3

1. •
   A plant of the species Dicentra cucullaria, native to eastern North America and the Columbia River basin.
2. •
   A plant of the species Lamprocapnos spectabilis, formerly Dicentra spectabilis, similar to D. cucullaria, but red or pink.
3. •
   (informal) Something proverbially blue, used in phrases relating to a clear blue sky, as in "enough blue sky to make [or patch] a Dutchman's breeches", etc.