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Slender, sharp beauty and its devotee, the rare forest ringlet butterfly - pēpepe pōuri


As far as native sedges go, Gahnia pauciflora is one of the most elegant. Its tufted form with bright-green to yellow green foliage is crowned with flower panicles held well above the razor-sharp leaves. Spectacular on banks and outcrops with its graceful, drooping flowerheads. This native perennial sedge definitely deserves plenty of room to showcase its form. A delightful addition to your garden and a very useful plant for dry dappled shade.



Gahnia pauciflora
Gahnia sp. in its natural habitat on a bank in a Kauri forest - Coromandel Peninsula. Photo by Gabriela V.

Its natural habitats are coastal to montane areas (up to 800m a.s.l.) from forest to shrubland. Flowering occurs from September through to January. The inflorescences are much branched with small, crowded wind-pollinated flowers, followed by fruits which may be present on the plant throughout the year.



Gahnia seeds
Seeds often stay on the plant throughout the year. Photo by Jeremy R. Rolfe
Gahnia seeds
Orange-brown nuts that feature a distinctive black apex. When chewed impart a distinct vanilla flavour. Photo by Gabriela V.

Gahnia pauciflora plays a crucial role in the ecosystem as it serves as both a host and food plant for the rare and beautiful forest ringlet butterfly (Dodonidia helmsii). This species is so specialised that it only lays eggs on a couple of species of native sedges.




This NZ native butterfly of the family Nymphalidae, is the only species in the genus Dodonidia. The forest ringlet butterfly is a strong-flying species, found in low to moderate altitude forests up to the tree-line, especially around open forest clearings.



forest ringlet butterfly
The markings on its wings give an impression of the eyes of a much larger animal, warning potential predators to stay away. http://www.aucklandmuseum.com/collections-research/collections/record/am_naturalsciences-object-692390?p=6&srt=az&pht=True&dept=entomology&ordinal=103#gallery

The adult female deposits her eggs on the underside of the sedge. They hatch in about three weeks. The caterpillars are nocturnal and feed on the "cutty sedge" (Gahnia) and bush snowgrass (Chinocloa) from spring to early autumn. They go into hibernation over winter, nestled in the base of the plant.



forest ringlet caterpillar
The luminous green caterpillars grow to about 34mm. Photo by Carey Knox. http://www.inaturalist.org/taxa/197071-Dodonidia-helmsii/browse_photos

By early summer, the fully grown caterpillars form a chrysalis, and 20 days later, a beautiful butterfly emerges. Forest ringlet butterfly live for approximately one month and can be spotted drinking the nectar of mānuka flowers.

With a bit of luck, you might be able to spot one this summer on your bush walk.







Source:


New Zealand Plant Conservation Network 2025. Retrieved from http://www.nzpcn.org.nz

iNaturalist NZ. Retrieved from http://www.inaturalist.nz

Nature's Grace Aotearoa. Retrieved from http://www.naturesgrace.co.nz

Nelson Natives. Retrieved from http://www.nelsonnatives.co.nz

Auckland Museum. Retrieved from http://www.aucklandmuseum.com

 
 
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