Skirts, scales, hexagons, and colour. There are many differences you can look out for if you want to learn how to identify tree ferns.
Ponga, mamaku, kātote, whekī, and whekī ponga are the most common tree ferns you’d encounter in New Zealand’s bush. We ask fern expert Leon Perrie: how do you tell the difference?
Mamaku | Cyathea medullaris
Would the arms (the frond stalks) of the tree fern beat you in an arm wrestle? If so, it’s most likely a mamaku (also known as a black tree fern).
These are Aotearoa’s biggest ferns – and one of the tallest in the world as they can reach 20 metres in height.
They’re easy to identify as their frond stalks are black and can be as thick as your arm!
Their trunks are covered in hexagon-shaped scars which have been created as their leaves fall away.
Remember: thick black frond stalks, hexagons on the trunk, tallest tree fern in NZ
Ponga | Cyathea dealbata (silver fern)
Are the underside of the leaves a white or silvery colour? If so, the tree fern is a ponga – the silver fern, a species of tree fern only found in New Zealand.
Ponga can also be identified by the white tinge of their fronds’ stalks. Plus, the fronds are covered with small scales, in contrast with the hairs characteristic of the Dicksonia species such as whekī (tree ferns are either scaly or hairy). Mamaku and kātote are also scaly tree ferns.
Ponga can grow up to 12 metres tall. They are sometimes referred to as ‘punga’ – this is a corruption of ‘ponga’, and is commonly applied to whekī or tree ferns collectively.
Remember: silver and scales
Kātote | Cyathea smithii
You can spot a kātote by its dead frond stems – which look like a skirt!
Notice in the image above how all the leafy parts have fallen off the dead fronds?
The kātote is more common in colder habitats, and grows up to 8 metres tall – so it doesn’t often reach the canopy.
Remember: skirt of frond stems
Whekī ponga | Dicksonia fibrosa
Like the kātote, whekī ponga retains a skirt of dead fronds, but the leafy parts of the fronds don’t fall off, so the skirt appears much fuller.
Another clear indicator that it’s a whekī ponga is its thick, soft, fibrous, rusty brown trunk.
They can reach up to 6 metres tall, so it’s a little shorter than the kātote.
Remember: full skirt with leaves still on the fronds, thick fibrous brown trunk
Whekī | Dicksonia squarrosa
A narrow dark brown trunk and skinny black frond stalks may mean you’re looking at whekī. The dead orange-brown fronds often give it a scruffy appearance.
The dense covering of brown hairs on the frond stalks is also a giveaway. Whekī ponga is also a hairy tree fern (but not as hairy as whekī!)
Most of the ‘punga trees’ you see for sale at garden centres are in fact whekī. They’re ideal for gardens and landscaping because they’re the only New Zealand tree fern you can cut the head off and it will grow back from buds on the trunk.
Whekī can reach about 7 metres.
Remember: hairy, skinny brown trunk, scruffy orange-brown fronds
Downloadable identification guide
Save or print a handy PDF poster to help identify the common adult tree ferns you come across.
More tree ferns
We’ve covered the most common tree ferns you might come across in New Zealand. But if you want to learn more:
Do you feel more confident with your tree fern identification? You could join iNaturalist. Here, you can upload photos of tree ferns you come across and the community can help you out with your identifications.