Photo by Bill Reynolds

Prairie blue-eyed grass (Sisyrinchium campestre) is misnamed. It is not a grass but a member of the Iris (Iridaceae) family. It is found in full sun in dry to moderately moist upland prairies, meadows, and sometimes woodland openings. It appears as a tuft of 2 to 6 narrow, grass-like leaves and one or more narrow flowering stems. The stems are leafless and conspicuously winged. From May to July a cluster of 1 to 11 flowers appears at the end of the stem. The flowers are pale violet, light blue, or white and have a yellow center.

There are four species of blue-eyed grass found in Minnesota and they can be difficult to tell apart. To identify the species take note of the waxiness of the leaves; the flower color; the number of flower clusters; the color of the bracts below the flower cluster (spathe), strongly tinged, lightly tinged, or not tinged at all; and whether the margins of the outer spathe bract are united at the base.

http://www.minnesotaseasons.com/Plants/prairie_blue-eyed_grass.html