Carex trifida

Carex trifida is a sedge indigenous to New Zealand, southern South Island, Stephens, Stewart, Chatham, Snares, Antipodes, Auckland, and Campbell Islands. It is also present on Macquarie Island, in southern South America and the Falkland Islands. 
It is an extremely robust, compact, light green to glaucous sedge, producing tussocks up to 1 m diameter.