Machaerina insularis is a flowering plant in the sedge family. The specific epithet is the Latin insularis (growing on an island), alluding to its island home.
It is a tufted perennial sedge, with erect, biconvex culms, growing to 1âÂÂ2 m in height. The smooth leaves are mostly basal, 1âÂÂ1.8 m long and 2âÂÂ3 cm wide. The inflorescence is much branched and 10âÂÂ20 cm in length. The fruits are narrowly ellipsoidal-trigonous brown nuts, 2 mm long.
The sedge is endemic to AustraliaâÂÂs subtropical Lord Howe Island in the Tasman Sea. It occurs on the rocky slopes and summits of Mounts Lidgbird and Gower at the southern end of the island.