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This article was published in ''Tararua Tramper February 2025
February in the hills with Michele Dickson and Chris Horne
name, here, here
Rumohra adiantiformis
Karuwhai, leathery shield fern, climbing shield fern
For general comments about ferns, see Asplenium oblongifolium in the October 2015 Tramper, and a description of the life cycle of ferns in Asplenium bulbiferum in the December 2015 Tramper.
Origin of the botanical name- Rumohra is named after a German patron of arts and science, Carl von Ru(h)mohr Holstein (1785-1843); adiantiformis is derived from ‘adiantum’, meaning shaped like ferns in that genus and ‘forma’ the Latin word for shape. It has been placed in the family Dryopteridaceae.
Distribution- Leathery shield fern / karuwhai is native to New Zealand where it occurs on Te Ika a Māui / North Island, Te Waipounamu / South Island, Rekohu / Chatham Island and Rakiura / Stewart Island. It is widespread in the Southern Hemisphere and also found in Central and South America, southern Africa, Madagascar, the Mascarenes, Seychelles. It is common on the ground in lowland to montane forest in the North Island, but rare in the South Island.
Growth habit and reproduction- Leathery shield fern / karuwhai is usually a climbing epiphytic fern, particularly on tree ferns, but occasionally on rocks or the ground. The fronds are 2 to 3 pinnate, very leathery and plastic-like to feel, glossy bright- green above and paler and duller below. The rhizomes which climb or creep are orange- brown, very scaly and about 5 mm diameter. The overall lamina / frond length is usually 20-90 cm and the stipes / stalks 10-35 cm long and densely scaly near the rhizomes. The sori, on the underside of the pinnae, are on either side of pinnae midribs, round, typically numbering 1 to 12, large, black at maturity, with indusia which have black centres.
Uses- We have not been able to find any uses for leathery shield fern / karuwhai.
Where to find leathery shield fern / karuwhai? Look for it in reserves in the Wellington area, the Tararua, Remutaka and Aorangi ranges, and wherever you tramp in native bush.
In The Hills 2024-12 < Index chronological > In The Hills 2025-03