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Kiss of life for rare dwarf mistletoe species

4 Apr 2023, 10:53 AM

A naturally uncommon mistletoe species that only grows in a handful of spots across the Kāpiti Coast has been given a kiss of life thanks to a decade of work by a local biodiversity champion.

Rhys Mills, Reserve Supervisor at Ngā Manu Nature Reserve has spent the last 10 summers painstakingly harvesting locally endangered Korthalsella salicornioides seeds, one of eight species of mistletoe found in Aotearoa New Zealand.

“Dwarf mistletoe is what we call a hemiparasite which means it can produce some of its own nourishment through photosynthesis but it needs to draw additional resources from a healthy host, mānuka in this case, for survival,” says Mills.

“We’re seeing incredibly heightened groundwater levels across the district which are effectively drowning two of the three main mānuka habitats where you could find mistletoe growing naturally.

“It’s an all-out effort to get as much seed out as possible now.”

Unfortunately, Mills’ ability to collect seeds this year was hampered by a hand injury, so he called on Kāpiti Coast District Council for some help.

“Rhys has really been an unsung hero in the conservation of this threatened species,” says Andy McKay Team Leader Environment and Ecological for Council.

“We’ve been more than happy to help out with harvesting this year at ecological sites in Waikanae Park, which has dying mānuka currently sitting in a metre of water,” says Mr McKay.

Collecting seeds isn’t as simple or easy as it sounds, however. This mistletoe sheds its seeds explosively, similar to a mushroom shedding spores. The seeds travel between 60 to 100cm from the plant into the surrounding canopy.

“We’re not sure what the release trigger is but we know that it generally happens in February for about four weeks. That means we need our sites prepped, ladders in place and manpower on standby by the end of January,” says Mills.

“The seeds are tiny so we set traps of fine mesh curtain secured by cable ties over each plant that catch expulsions. We need to check the cloth every 24 hours and when we find seeds, we use a slushy straw to gently scrape them off into an old pill canister.

“To help the seeds stick to a new host, they are ejected with a gelatinous substance that dries on the cloth, so we dampen it to help remove them, then sow onto new hosts in a safer ecosystem. We spray them with a 10 percent solution of PVA glue and water to reduce transpiration.”

Mills says that over the years he has experimented with locations, including a successful planting programme at Ngā Manu Nature Reserve.

“Dwarf mistletoe needs a dense canopy habitat of either kānuka or mānuka so that the seeds can spread but we don’t have that at the remaining sites in Kāpiti anymore. Our species prefers mānuka which only has a 20-year lifespan so I’m now trialling seeds on kānuka as it has a lifespan of up to 120 years,” says Mills.

“Humidity is important for success, too. Seeds take better by open water so I think if we can do some planting on the edge of the wetlands in Waikanae Park, we’ll have a good shot at reintroducing dwarf mistletoe back to the area in the future – but it will be years away.”

So, after countless hours, year upon year, dedicated to saving a tiny exploding native parasite, has it all been worth it? Mills thinks so.

“Native mistletoe is extremely overlooked and gets a bad rep as a parasite but we have to remember that not all parasites are bad,” says Mills.

“So many of the modern and traditional medicines we rely on originate from compounds found in plants. What if there is something that could be important in mistletoe? I think it’s worth saving. If we lose it, it’s gone forever.”

Mills celebrated 30 years of tenure at Ngā Manu in February, a huge achievement and testimony of his dedication to conservation work in Kāpiti.