This genus is known best for Ophiopogon planiscarpus nigrescens, the 'black grass', but there are others that are also useful as foliage plants, with tufts of grassy leaves.
Ophiopogon planiscarpus 'Kokuryu' you either love or hate. The tufts of narrow, grassy leaves are shiny, jet black, and spread slowly by stolons. It does have flowers, a few small pink or white ones on 30 cm stems, followed by dark blue fruits, but these are not particularly visually important. Its role is as an architectural foliage plant, the black contrasting strikingly with lighter colours of its neighbours.