Gahnia radula, common name "Thatch saw-edge", is wide spread on Knocklofty Reserve especially in the sandstone area south east of the Forest Road carpark and along the upper side of the Main Trail near the Glover Track junction. This species is the only food and habitat species for the rare and endangered butterfly species, Chaostola skipper. The Chaostola skipper caterpillar binds 2 or 3 of the Gahnia radula's strappy leaves together about half way up their length and forms a round cocoon in which the caterpillar spends the day upside down for about two years. At night the caterpillar climbs down out of the cocoon and feeds on the edges of the Gahnia radula leaves near their top. Gahnia radula grows 0.3 to 2m high by 0.3 to 2m wide as a clumping perennial herb, spreading by underground rhizomes (roots that have nodules from which new surface stems can grow). It has deep green, rough, sharp edged leaves up to 2m long by 6mm wide and dark brown, sometimes pendulous flower stems off the leaf stems up to 60cm long by 7cm wide. It prefers damp soil but can tolerate extended dry periods and frosts. This species is also known to be used as nesting sites for Blue wrens and the seeds provide food for Rosella parrots. The foliage has been used for roof thatching, hence the common name.