Sisyrinchium angustifolium (Blue-eyed Grass) Ephemeral This perennial plant is short

This perennial plant is short in height

via Wikimedia Commons

Could be a nice replacement or substitution for boxwood

Valérie75 assumed (based on copyright claims)

the tuft forms above the waterline creating a tussock sedge meadow

Sisyrinchium angustifolium (Blue-eyed Grass) Ephemeral This perennial plant is shortClusters of beautiful violet blue flowers appear in spring on stalks emerging from very attractive grass like leaves. The plants are fairly easy to grow and will gradually form larger clumps that will impress as a border planting, rock garden, edging along paths or cottage gardens. Interestingly enough, blue eyed grass belongs to the iris family and not the grass family Sun Exposure Prairie Soil Conditions Wet Mesic, Mesic Height 8" 1' Flower Color