Carex secta is a common endemic sedge of coastal to montane swampy areas throughout New Zealand from sea level to 900 m. It is found throughout the North, South, Stewart Islands and also on the main Chatham Island, though it is scarce there.
It is a tussock forming sedge up to 1.5 x 1.5 m. Older plants in moist to wet sites, often form thick trunk-like bases 1 metre tall comprised of matted rhizomes, roots and old culm bases. It grows only in still, not flowing water.
Carex secta takes on a yellow-green colour in open situations with the colour being intensified in the winter.
Flowering can occur from September to December with fruiting occurring October to March.