Te Papa’s orchid specialist Carlos Lehnebach and research technician Jennifer Alderton-Moss from the Lions Ōtari Plant Conservation Lab are celebrating a major breakthrough after the threatened swamp greenhood orchid blooms for the first time in cultivation, marking a significant milestone for conservation and recovery efforts.
The swamp greenhood orchid (Pterostylis micromega) is one of 30 species of greenhood orchid found in Aotearoa New Zealand. Unlike many of its relatives, which normally grow in grasslands, scrub, or forests, this orchid is a wetland specialist. Sadly, wetlands are one of our most threatened ecosystems – today, only about 10% of Aotearoa’s original wetlands remain, largely due to urban and rural development.
Historical specimens held at Te Papa’s herbarium confirm that the swamp greenhood orchid was more widespread than it is today. Collections made in the late 1800s and early 1900s confirm this orchid was present in wetlands on Rēkohu Chatham Islands, and Kaitaia, Northland, respectively. While photographic record confirms it once flourished in Upper Hutt, Wellington! Today, the swamp greenhood orchid is only known from a handful of sites in the North Island and a single location in the South Island.
The swamp greenhood orchid is an endemic species, meaning it is found nowhere else in the world. If known populations continue to decline, or altogether disappear, this unique orchid could be lost forever. The risk of extinction for the swamp greenhood orchid is so high that experts have classified it as a Threatened – Nationally Critical species, the most severe conservation status for any New Zealand living species. This is the same conservation status as the kākāpō.
Dealing with a difficult species
Greenhood orchids have a specialised pollination systems and specific seed germination requirements. Greenhood orchids are easy to recognise due to their distinctive hood-shaped flower formed by the fusion of the sepals and petals. Another unique feature of these orchids is their sensitive lip, a highly modified petal, which quickly flips inwards when an insect lands on its tip, temporarily trapping it inside the hood. The only escape route for the insect involves pushing past the orchid’s reproductive organs. This action ensures pollination takes place and fruits are formed.
After pollination, the orchid will form a fruit and once it matures, it will split open and the orchid’s dust-like seeds will be dispersed by wind. Each fruit forms thousands of seeds but only those encountering a specific soil fungus will germinate and grow to adulthood. Unlike many other plants, orchid seeds do not store food resources, so the fungal strings (hyphae) act as an umbilical cord, moving nutrients from the soil into the embryo.
Understanding how the fungal-orchid interaction works, identifying the orchid’s preferred fungal partner, and being able to recreate the germination process in the lab are crucial steps to help us in the conservation of the swamp greenhood orchid.
Propagation success at the Lions Ōtari Plant Conservation Lab
After two years of research at the Lions Ōtari Plant Conservation Lab and Te Papa, in collaboration with the Department of Conservation and the Waikato Regional Council, we have cracked the code for germinating seeds of the swamp greenhood orchid under lab conditions using its preferred fungal partner, a member of the Ceratobasidiaceae family. We have also figured out how to transition seedlings from this protective environment into the “real world” without killing them all!
This breakthrough has significant implications for the conservation and long-term survival of this orchid. So far, we have produced more than 80 plants from a population in the Waikato region. Meanwhile, from two capsules collected from a population in the South Island, we have generated more than 500 seedlings. Twenty of these seedlings have now returned to their original population, where only 13 individuals have been previously recorded.
To add to our excitement, some plants are now flowering at the nursery! From seed to adult plant, this has taken two years. We will hand-pollinate these flowers to produce more seeds and grow more plants. These plants can be used for reintroduction into suitable wetlands, to support research on the species pollination system, serve as a backup in case the original population is lost, and used in public events so we can share the beauty of this rare orchid with the community.
It has been more than 20 years since the swamp greenhood orchid was formally listed as a threatened species. Thanks to our research, support from funding agencies, a network of collaborators, and the facilities at the Lions Ōtari Plant Conservation Lab, we can now, for the first time, prevent further declines in its population and reintroduce it to wetlands were they once flourished. We are hopeful that our work will help to remove this unique species from New Zealand’s threatened plant list.
Acknowledgements
Many thanks to Karin van der Walt (former Conservation and Science Advisor – Ōtari Native Botanic Garden) for her rigorous research and persistent advocacy for these and other New Zealand threatened plants and to Phoebe Smith (former Horticultural Intern – Ōtari Native Botanic Garden) for her patience and care in teaching our babies to harden up and survive out of the lab. We are very thankful to the Te Tahua Taiao Nga Taonga Lotteries Environment and Heritage Fund and the Stanley Smith Horticultural Trust for their financial support.
