Three Te Papa botanists recently visited Norfolk Island together with colleagues from the Royal Botanic Gardens Victoria. Their purpose was to collect ferns for research. Curator of Botany Leon Perrie introduces the significance of Norfolk Island’s ferns.
Our research programme investigating the relationships and naming of Aotearoa New Zealand’s ferns depends on also understanding the ferns of the surrounding landmasses. For example, more than half of New Zealand’s indigenous ferns are thought to also occur naturally elsewhere, especially south-eastern Australia and the Pacific Islands.
While we’ve been involved with many studies of Australian and Pacific Island ferns, samples from Norfolk Island have been mostly missing from our work – until now.
Norfolk Island is a small archipelago with a land area of about 35 km2 and a volcanic origin within the last few million years. It lies on the otherwise submerged Norfolk Island ridge between New Zealand and New Caledonia, and is an external territory of Australia.
Despite its small area, about 45 species of ferns (and lycophytes) are native to Norfolk Island, compared with 204 for New Zealand.
Fern names belonging to Norfolk Island
One of the reasons why the ferns of Norfolk Island are significant is that several scientific names of wide-ranging species ‘belong’ to Norfolk Island. That is, the type specimen(s) for the names were collected from Norfolk Island. It is as many as seven and reflects that European settlement of Norfolk Island was comparatively early for the region.
All photos are from Norfolk Island unless specified. The colloquial names are those from Norfolk Island.
Ferns endemic to Norfolk Island
Also significant is that six fern species (and one subspecies) are endemic to Norfolk Island. Although found naturally only there, all have close relatives in Australia or New Zealand.
Asplenium dimorphum is one of the parents of the widely-cultivated false hen and chickens fern, Asplenium ×lucrosum. The other parent is Asplenium bulbiferum, the ‘true’ hen and chickens fern, which is endemic to New Zealand.
After our role in elucidating the identity of Asplenium ×lucrosum, we were pleased to see Asplenium dimorphum in the wild for the first time. It’s a common species on Norfolk Island, and perhaps the most iconic of the ferns there.
Ferns shared by Norfolk Island and New Zealand
The following are some of the fern species indigenous to both Norfolk Island and New Zealand.
Ferns not shared with New Zealand
Norfolk Island also shares several ferns with other places that are not in New Zealand, such as the following. New Zealand is probably too cold.
Unfortunately, about 10 species of exotic ferns have established on Norfolk Island. Those that are actively spreading have the potential to displace native species. The following three examples are also weedy in New Zealand.
Thanks to: our colleagues Daniel Ohlsen and Misha Chute from Royal Botanic Gardens Victoria; Kevin Mills for sharing information about Norfolk Island’s ferns before our trip; and to the local rangers for their support.