Hapu'u (Cibotium Sp. ) Hawai'i has three species of tree ferns, all of which are native. They grow up to 40 feet in height in shady, wet forests. One species, hapu'u pulu, has a silky golden fiber growing at the bases of the fronds. Called pulu, the fiber was exported during the late 1800's for pillow arid mattress stuffing. Another species, hapu'u 'i'i, has stiff blackish hairs at the bases of the fronds. The tree ferns contain a starchy core which is eaten by the many feral pigs inhabiting the Park. A trough is left where rainwater may collect and provide a breeding place for mosquitoes. The mosquitoes can transmit avian malaria, one cause of the decline and extinction of the native birds of Hawai'i.