The King fern (Ptisana salicina) is the only New Zealand native representative of the Marattiaceae (and was formerly known as Marattia salicina). This is a group of ferns most closely related to the horsetails but with the largest fronds of any ferns.
King fern is found throughout the Pacific but in New Zealand is found throughout the north-western half of the North Island from inland Wanganui northwards. The Waikato is probably its stronghold where it is known from many remnants and forested areas in the west. In New Zealand it appears to favour lowland, karst habitats and dark stream sides, often amongst supplejack (Ripogonum scandens) and parataniwha (Elatostema rugosum).
For more information about the Marattiaceae: