Sisyrinchium spp. (Blue-Eyed Grass)

Clump-forming perennials that bloom seemingly nonstop throughout the summer.  Many of the sisyrinchium species set seed rather freely and can become a nuisance but the following cultivars are all sterile (or set seed very seldomly) and will only form tidy clumps wherever planted. 

Requirements: Full sun and well-draining soil. Drought tolerant.