Bringing the swamp helmet orchid back from the brink of extinction is a mission that requires a multidisciplinary team of scientists, good eyesight and a lot of patience. There are only a few hundred plants of this species in the world; all of them are here in Aotearoa New Zealand. Curator Dr Carlos Lehnebach talks about his latest research to save this species.

Somewhere, within a 7,000-hectare wetland hides the swamp helmet orchid (Corybas carsei), a tiny orchid on the brink of extinction. This orchid belongs to the genus Corybas, a group of terrestrial orchids commonly known as helmet or spider orchids.

There are more than 100 species of Corybas in the world, mostly distributed across Australasia, New Zealand, some Pacific islands and a few sub-Antarctic Islands. In New Zealand, there are 22 species. Corybas carsei is the rarest and the smallest of all.

The orchid formally known as …

This orchid was formally described as Corysanthes carsei in 1911 by the former director of the Auckland Museum, Mr Thomas Cheeseman. The samples he studied were collected from a swamp near Kaitaia (Northland, North Island) by Harry Carse (1857–1930) and Richard Henry Matthews (1835–1912). These samples are now in our botany collection.

Carse and Matthews were self-taught botanists. Carse was a school teacher in Kaitaia and Matthews a jack-of-all-trades (builder, farmer, gold miner, school superintendent, and at one stage he also ran Kaitaia’s first post office). Matthews’ son, Henry Blencowe (aka Blen) shared the two men’s interest in native plants and would tag along on many of their collection trips.

After this first collection, the swamp helmet orchid has been found in at least three other wetlands in New Zealand. However, draining and conversion of these wetlands into agricultural or horticultural land has wiped out this orchid from all sites but one.

The only existing population is at the Whangamarino Wetland in the Waikato (North Island), where almost 400 plants grow over an area no larger than three carpark spaces.

Kaitiakitanga of the population

Since the 1980s the Department of Conservation has devotedly looked after this population. Every year rangers visit the site to assess the health of the population and its habitat.

They count the number of plants at the site as well as the number of flowers and fruits formed every spring. They also keep the surrounding vegetation under control so it does not smother the tiny orchid, which thrives in open spaces. Their aim has been to increase the size of this population.

Between 2020 and 2022, conservation of the swamp helmet orchid took a new turn. With a larger population available, research to understand the orchid biology and the genetic diversity within the population was possible.

This was the perfect opportunity for me to apply the knowledge I have learned over the years about orchids. Orchid conservation though is not a one-man job and this project required the assemblage of a multidisciplinary team.

Our team included two postgraduate students (Tingyu Quin and Jennifer Alderton-Moss) which I co-supervised with scientists from Massey University (Dr Alastair Robertson, Dr Vaughan Symonds, Dr Jennifer Tate), Victoria University of Wellington (Dr Andrew Munkacsi) and Ōtari Native Botanic Garden, Wellington (Dr Karin van der Walt).

The group at Massey University investigated the genetic diversity within the population and the pollination mechanism used by the orchid to form seeds. The team based in Wellington focused on the orchid-fungus partnership, which is essential for seeds to germinate.

Despite the many challenges imposed by COVID lockdowns and unpredictable weather, over the last two years, we have managed to gain a good understanding of this rare orchid. Results from our research, funded by the Department of Conservation, will help us to implement methods to further increase the size of the population at the Whangamarino Wetland.

In the long term, we hope to grow sufficient seedlings to plant in suitable wetlands within the orchid’s original distribution and to create ‘backup’ populations ex situ (e.g. in botanic gardens).

Both MSc students have now completed their theses and a number of publications will follow soon. While we wait for the scientific articles to appear, I will be blogging about our journey to save this tiny orchid from extinction. Come back for more!

Further reading

• Henderson, J. 2021. Record numbers of rare Whangamarino orchid allows new research.
• Lehnebach, C. 2022. Research supporting the conservation of the Nationally Critical swamp helmet orchid (Corybas carsei). Trilepidea 217: 1-4.
• Smith, V. 2008. Eponymus orchids. New Zealand Native Orchid Journal 109: 22.
• Smith, V. 2009. Eponymus orchids. New Zealand Native Orchid Journal 111: 14.