A species of sedge hiding under our noses for over a hundred years has been revealed by Te Papa’s Science Researcher Lara Shepherd, Botany Curator Leon Perrie and the University of Auckland’s Marley Ford.
Schoenus vacillans is a sedge described from Coromandel in 1878. However, botanists since 1906 have considered it as simply another form of the common bog-rush (Schoenus apogon), which occurs in New Zealand, Australia, Taiwan, New Guinea and possibly Japan.
Whilst examining specimens of the common bog-rush in Te Papa’s herbarium for an earlier study, Lara and Leon thought that the specimens matching S. vacilllans were strikingly different from the remaining common bog-rush specimens. The flowerheads of S. vacillans have few flowers and are loosely clustered, compared with the densely clustered flowerheads of common bog-rush.
With the help of Marley, who lives and works in Northland, we obtained samples for DNA analysis and the results were clear – Schoenus vacillans is a separate species from S. apogon! In fact, the two aren’t even each other’s closest relatives.
Schoenus vacillans has only been recorded from a handful of locations, all in the northern half of the North Island. However, many of the records are over 30 years old and known populations are small. Schoenus vacillans tends to grow in disturbed sites, such as regenerating slip sites. Schoenus vacillans seems to be found only in New Zealand, being distinguishable from similar plants in Australia.
With fewer than 250 mature plants currently known, Schoenus vacillans fits the criteria for a threatened species and we suggest it should be ranked as Nationally Critical, the most serious conservation ranking in New Zealand. We hope that our reinstatement of S. vacillans as a distinct species prompts searches for previously recorded populations as well as new populations.
Our results have just been published in the New Zealand Journal of Botany.
