Two of our most common NZ tree ferns, are both prevalent in the Tawa native bush reserves.
Mamaku
Our tallest tree fern, reaching up to 20m, mamaku (black tree fern/Cyathea medullaris) has distinctively black, scale covered koru as the fronds unfurl.
The fronds extend up to 5m and can be as thick as a human arm at maturity.
Mature trunks are distinctive with their oval to hexagonal scar marks left when fronds have fallen off.
Examples of mamaku are obvious at the side of the ascending track in the Te Ngahere-o-Tawa/Forest of Tawa.
Ponga
Ponga (silver tree fern/Cyathea dealbata) is an iconic symbol of New Zealand. With its distinctive silvery underside of the fronds being replicated as an emblem for our national sports teams. Names relating to this fern have also been adopted, including the ‘Silver ferns’ (netball) and the ‘White ferns’ (women’s cricket). Also, for Air New Zealand, our national airline, aircraft have the silver fern replicated on the fuselage of their planes.
Reaching up to 10m in height, the silvery underside to the fronds appears after plants are about 4 years old. The mature trunks have their surface covered with ‘peg-like stumps’, where the fronds were once attached. Many specimens are visible near the tracks in Redwood Bush.
Which fern is which when I see them in the bush?
View the underside of the fronds and examine the nature of the trunk where fronds have fallen off
Article Source: Gil Roper December 2020
Friends of Tawa Bush Reserves 