There are two main groups of tree ferns in New Zealand: Cyathea and Dicksonia. They are easily distinguished since Cyathea is scaly and Dicksonia is hairy.
There are seven Cyathea species native to New Zealand. Five are endemic to New Zealand, with Cyathea cunninghamii also occurring in Australia and C. medullaris being recognised from several Pacific Islands. Two of the New Zealand species are confined to the subtropical Kermadec Islands: C. kermadecensis and C. milnei. An Australian species, C. cooperi, has been recorded as a weed in New Zealand. Sometimes several genera of scaly tree ferns are recognised alongside a more narrowly-circumscribed Cyathea, in which case the New Zealand species are placed in Alsophila except for C. medullaris which is placed in Sphaeropteris.
There are three Dicksonia species native to New Zealand. Additionally, New Zealand is the only home of Loxsoma, which is related to tree ferns but does not form a trunk.
The most frequently seen species of tree fern in New Zealand are Cyathea dealbata (silver fern), C. medullaris (mamaku), C. smithii (katote), and Dicksonia squarrosa (wheki).
Tree ferns are colloquially known in New Zealand as “pungas”. This appears to be an English corruption of “ponga”, a name specific to Cyathea dealbata (silver fern). Most punga trunks for sale are not actually ponga but wheki (Dicksonia squarrosa). If you want to make a wall of tree fern trunks that have a reasonable chance of coming back to life, ask for wheki.