Blue-Eyed Grass (Sisyrinchium montanum) The tiny (1.5 cm), delicate, lily-like flowers of blue-eyed grass open briefly in mid-June. The leaves of this diminutive iris resemble a clump of stout grass, only reaching to about 20 cm high. It is a wide-spread, though seldom seen plant on the prairies. In sandy soils it can form large clumps (15 cm across) with many flowers open at once, but it is more usual to chance upon single flowers scattered among the grasses in moister prairies.