New alpine buttercup revealed

Click to enlarge
Build me up, buttercup: Ranunculus acraeus, in full bloom. Photo: Ann Cartman

www.landcareresearch.co.nz

New alpine buttercup revealed

A rare and beautiful alpine buttercup with large yellow flowers has been identified in North Otago mountain ranges.

Landcare Research botanist Dr Peter Heenan has named it Ranunculus acraeus1 . The genus Ranunculus includes buttercups, and acraeus means “on high”, a reference to its alpine habitat. The plants are up to half a metre across, and form numerous shoots with brilliant yellow blooms 4–5 cm wide.

R. acraeus is found on boulder fields at heights upwards of 1500 metres on mountains mainly to the south of the Waitaki Valley in North Otago. The largest population (about 200 plants) was found on Mt St Mary in St Mary’s Range. Much smaller populations (three to four plants only) were found on mountains around the Ohau skifield and near Tekapo.

Older herbarium specimens of what is now known as R. acraeus were collected from the Hawkdun Range.

Dr Heenan says based on current distribution and abundance information, the newly described R. acraeus qualifies as acutely threatened and nationally critical. “However, field surveys are needed for more accurate knowledge on the distribution, abundance and threats the plants face.

“Introduced herbivores, particularly thar and chamois, are known threats to the new buttercup, just as they are to other alpine plants such as the Mt Cook lily. While our team was researching R. acraeus in its habitat, we witnessed browsing damage, and thar were nearby.”

R. acraeus looks similar to R. piliferus, a buttercup that lives on boulder fields in Southland and South Otago. Dr Heenan’s research has seen R. piliferus recognised as a separate species rather than as a subspecies of R. haastii, a small tufted alpine buttercup from Canterbury and Marlborough. R. acraeus is an entirely new species.

Dr Heenan says it is always great to see detailed botanical research rewarded with the recognition of a new species, and in this case a particularly attractive one.

“It highlights the value of combining morphology – study of the form of the plant – with DNA and fieldwork. The DNA research was undertaken by colleagues at Massey University.

“The find caps off a long list of new discoveries in the past six years, which shows there is still much to learn about our native plants.”

Dr Heenan says although the beautiful newly described buttercup would look great in a garden, he’d recommend that nobody removes it from its alpine lair.

“Besides the fact you’re tampering with a rare native plant, the buttercups don’t grow well at lower altitudes.”

1 Pronounced “ah-CREE-us”

ENDS

© Scoop Media