Rare endemic plant species healthy in Horizons Region

Dactylanthus taylorii, commonly known as pua o te reinga or wood rose, was discovered by Horizons senior biodiversity advisor Zoë Stone on a routine visit to a Rangitīkei property.
 
Dr Stone says the discovery is an exciting one because of its location in the region.
 
“Most populations of Dactylanthus in our region are found in and around the central plateau, so finding a population this far south is really exciting.”
 
Dactylanthus taylorii is New Zealand’s only fully parasitic flowering plant, says Dr Stone.
 
“It invades the roots of its host species and forms rhizomes, which it uses to get nutrients from the host. The name ‘wood rose’ refers to the unique flower-like formation which the host plant forms when Dactylanthus attaches to its roots.
 
Dr Stone says the plant is under threat from declining pekapeka (short-tailed bat) populations.
 
“Dactylanthus is at risk of extinction due to the loss of pekapeka from many sites.
As the main pollinator of Dactylanthus, the relationship between the two species is vital for its survival.
 
“Our biodiversity protection work through our Priority Habitats Programme helps to address some of these issues, but without intervention these plants would likely not survive.
 
“We’re now planning to monitor for pekapeka on the property to see if they are present. If there is no active population, we may need to give the plant some help with hand pollination.”
 
Dr Stone says the property where the species was found is uniquely biodiverse, and is actively managed under Horizons’ Priority Habitats Programme.

“The site contains a rare fragment of critically endangered rimu, mataī, and hīnau forest. Only 3% of this ecosystem remains in the region.
 
“As part of the Priority Habitat Programme, Horizons works with the landowners to help protect this rare forest fragment. On this property, we have active old man’s beard control and possum control programmes underway, which support forest regeneration and improve protection of native birds, reptiles and invertebrates.”
 
Dr Stone says the landowners were thrilled to hear of the discovery.
 
“They’re very motivated to work with us to help protect the individuals we’ve found, and we’re now exploring options to locally protect these unique plants.”
 
The main threat to Dactylanthus is possums eating the flowers, says Dr Stone.
 
“Possums are attracted to the sweet-smelling blooms when Dactylanthus is in flower, causing damage to the plant and interrupting its ability to set seed. As a result, many populations are slowly declining,” she says.
 
“Finding so many live specimens of Dactylanthus is possible evidence that the possum control measures in place are working to reduce possum populations in the area.”
 
Horizons biodiversity, biosecurity and partnerships manager Craig Davey says Council has earmarked funding to expand possum control operations through the 2025-26 Annual Plan.
 
“This significant investment will enable us to expand our current network of 210,000 bait stations and expand into at least four new areas of the region, that were previously controlled by OSPRI.
 
“Our possum control programme currently covers 1.6 million hectares of the region, and provides protection to primary production and allows native biodiversity to flourish,” he says.
 
“To keep up the gains, it’s key to continue funding and expanding the network so we don’t lose this momentum.”
 
Dr Stone says the most effective method to protect Dactylanthus from possums is placing cages around the plants.
 
“The cages stop the possums from being able to access the plants, while still allowing pollinators access. It’s important for the future of the species to protect this process.
 
“It may seem like a small discovery, but these little wins are really rewarding. It means the actions we’re taking to help to give our native biodiversity a fighting chance are making a difference,” she says.

Image: A healthy Dactylanthus plant found on the property.