By Trish Grant, Communications Advisor, Nelson
Over the summer DOC rangers have made exciting rediscoveries of a native herb thought to be extinct and another herb believed extinct in the wild.
The thought-extinct herb Dysphania pusilla (pygmy goosefoot) was, by coincidence, discovered growing in abundance around the same time in both Canterbury’s Mackenzie Basin and Molesworth Station in South Marlborough.
Dysphania pusilla was last recorded 56 years ago and three years ago it was declared ‘presumed extinct’.
Nelson Senior Ranger, Shannel Courtney, and Takaka Ranger, Simon Walls, found Dysphania pusilla growing in a dried-up pond bed in the Clarence River Valley in January during a flora and fauna survey.
Also in January, Twizel Senior Ranger, Aalbert Rebergen, was at the Ruataniwha wetlands in the Mackenzie Basin to take a photo of a rarely-seen white-winged black tern.
On entering the wetlands, he immediately noticed an abundant ground cover of a dark brown Atriplex-like plant. Its starfish-like growth-form and flat growing habit were very distinct, he assumed it was an exotic species.
Aalbert sent photos of the plant to botanists to identify. He received suggestions of other species in the same family, but he was sure it wasn’t them.
Determinedly, he pursued identifying the species, sending photos and some plants to another botanist and a herbarium and received confirmation it was Dysphania pusilla.
A few thousand plants are estimated at both locations and it was found growing at other sites in the Ruataniwha wetlands and along the banks of the Clarence River.
It was also found in late March in the Heron Basin in mid-Canterbury by plant ecology technical advisor Nicholas Head.
Shannel says the rash of discoveries creates speculation Dysphania pusilla could lie dormant as seed for years until favourable conditions trigger it to germinate, such as possibly a wet spring preceding a very dry summer.
Rediscovering one of eight native plant species listed as extinct is amazing enough but remarkably another herb thought to be extinct in the wild has also been found over the summer in the same area of Molesworth Station.
The last previously known wild population of Leptinella filiformis (slender button daisy) was destroyed in North Canterbury in the late 1990s, though it was being cultivated at some protected sites
Wairau ranger Jan Clayton-Greene had been on the lookout for Leptinella filiformis for 15 years when she first came across it in the Clarence Valley in 2011, without recognising it.
“I came across it by chance while looking for other species and didn’t realise at the time I had hit the jackpot in finding it. The plants I saw were scruffier than the lush ones I had seen growing in pots,” says Jan.
Jan collected and pressed a specimen and it was later identified as Leptinella filiformis. She and other staff collected more specimens from the same spot in January this year, when low river levels allowed access, so they could be grown on to enable the species to be confirmed.
The discovery of these small but special species highlights the importance of understanding our dryland ecosystems which increasingly are coming under pressure for development.
Many of these areas contain a large number of unique species which we are only just starting to learn about.