Carex horizontalis, known as bastard grass, hook sedge, or matua in te reo MÃÂori is a species of sedge, endemic to New Zealand. It is not a grass but a sedge.
This species forms thick, dense tufts. The culms are from 10âÂÂ40 cm, droop, and are hairless. There are 4-7 leaves per culm, and they are bright green, wide, soft, and channeled.
C. horizontalis is distinguished from the very similar Carex minor by its dense, tufted growths, its slightly larger (1.5âÂÂ2 mm wide) leaves, and its later flowering from October to November.
This species is found on the North Island, South Island, and in the Chatham Islands. It is found in forested areas, and at elevation from 300âÂÂ1000 m above sea level in the North Island.
This species is one of many other species in Carex, which are collectively known for having hooked rachillae. This allows the spikelets to get caught on fur or feathers from animals, allowing them to hitch a ride on a moving creature in order to spread geographically.
The name "bastard grass" may come from the hooked rachillae, which are annoying and difficult to remove from clothing, hair, or skin.
This species has in the past been put into the genus Uncinia.