In 2015, ecologists Chris Stowe and Claire Newell found a strange fern during a vegetation survey in Whirinaki Forest, in the eastern North Island. They sent a frond to Te Papa’s fern experts Leon Perrie and Patrick Brownsey, who were also puzzled. This fern was clearly a Dicksonia tree fern but didn’t match any known species. Was it a new species?
Te Papa’s Leon Perrie and Lara Shepherd travelled to Whirinaki to see this strange fern and found about 80 individual plants.
These ferns had fronds like those of the trunkless stumpy tree fern (Dicksonia lanata) and a trunk like whekī-ponga (Dicksonia fibrosa).
Genetic analysis of the ferns showed that they were not a new species. Instead they were hybrids between stumpy tree fern and whekī-ponga. This was an unexpected result because, unlike many other fern groups, Dicksonia ferns only rarely hybridise.
Even more interesting is that the two parent species are not even closely related to each other. They are thought to have diverged from each other 55 to 25 million years ago – yet they can still hybridise! For comparison, cattle and sheep are thought to have separated less than 20 million years ago.
This study has now been published: