Cyperus ustulatus, also known as giant umbrella-sedge or coastal cutty grass is a species of sedge native to New Zealand. C. ustulatus generally grows in coastal or lowland areas near water in the North Island and on the Kermadec Islands.

The leaves are wide, shiny and folded. It produces long, dark brown seed heads after flowering in summer. The seed heads are held by a cluster of leaves at the top of the plant.