Critically endangered Northland lake plant voted NZ’s favourite plant 2024

A tiny and very rare Northland lake plant, Trithuria inconspicua, has been voted ‘New Zealand’s Favourite Plant’ in a national poll.

The online vote was run by the New Zealand Plant Conservation Network (NZPCN) to find the native plant best-loved by New Zealanders.

Trithuria only grows in Te Taitokerau’s dune lakes and is found nowhere else in the world.

Trithuria-inconspicua. (Photo credit: Dennis Gordon - NIWA).Tiny in stature, Trithuria packs a mighty punch in age - the latest scientific research has revealed this little plant to be in the oldest flowering plant lineage.

Trithuria is in a plant family that has been around for over a hundred million years, so it is a ‘living fossil’.

The plant certainly lives up to its name of ‘inconspicua’. At only 55 millimetres tall, it grows partially buried in the sands of the lake floor, so you are more likely to feel it beneath your feet than see it. It has fans of fine, hair-like leaves in which it hides tiny flowers that look like miniature waterlilies.

Northland Regional Council (NRC) works in partnership with mana whenua, landowners and the Department of Conservation (DOC) to protect dune lakes and is delighted to celebrate Trithuria’s success.

“It’s so exciting that a Northland aquatic plant has won, and that people know and love this remarkable little plant,” the council’s Biodiversity Manager Lisa Forester says.

Kaumātua Ric Pārore, speaking on behalf of Te Kuihi hapū, one of the mana whenua of Kai Iwi Lakes, says they’re thrilled to see Trithuria recognised, but also sad the plant has become so rare.

“It’s important that everyone who visits or uses our lakes is careful to look after them so this plant can thrive.”

Unfortunately, the future for Trithuria is uncertain.

It is listed as ‘Threatened-Nationally Critical’, the highest threat category. Plant populations were previously found in 13 dune lakes north of Poutō, but since 1998 these have declined to viable populations in only five lakes.

Trithuria needs clean sand and water to survive and is effectively a ‘canary in the coalmine’ as far as water quality is concerned. It is threatened by deteriorating water quality due to nutrient enrichment, pest weed and pest fish impacts and recreational pressures.

Three of the lakes where Trithuria grows are public lakes where people like to swim or boat, which puts the plant at extra risk from being trampled or from accidental pest introductions.

Northland Regional Council, in conjunction with mana whenua, DOC and landowners, is currently running eradication programmes for hornwort and oxygen weeds in several high value dune lakes.

Councillor Jack Craw, who chairs the council’s Biosecurity and Biodiversity Working Party, says Te Taitokerau’s dune lakes are one of our outstanding ecosystems and are globally rare.

“Trithuria is a wonderful example of why these lakes are so special and its recognition as plant of the year is a reminder to us all of the importance of caring for our dune lakes.”

Councillor Craw says dune lakes and their biodiversity face many threats, including the risk of introduced pests like the invasive gold clam, which is now present in the Waikato River area.

“If this got into our lakes it would be disastrous and would almost certainly lead to the extinction of Trithuria in those lakes.”

He says Northlanders can help prevent the spread of aquatic pests by following ‘Check Clean Dry’ procedures when visiting the lakes.

If you do see Trithuria, the NRC urges you not to pick it, dig it up or trample it...just leave it undisturbed. (It is very difficult to grow and will not survive in an aquarium or home pond.)

For more information on this special plant visit: www.nrc.govt.nz/trithuria