Cyathea cunninghamii

gully tree fern, slender tree fern

Cyathea cunninghamii is widespread in the North Island, albeit more common in the wetter west, and scattered on the northern and western coasts of the South Island.  It favours gullies and river banks.  It also occurs in Australia.

It looks like a slender-trunked Cyathea medullaris but has shorter fronds and thinner frond stems.  However, it is actually more closely related to C. smithii.  As tall adults, C. cunninghamii and C. smithii are easily separated: C. cunninghamii has a clean trunk, whereas C. smithii retains a ‘skirt’ of dead frond stalks.  However, both species can have untidy skirts when young (even c. 2 m tall).

Cyathea cunninghamii can be distinguished from C. medullaris and C. smithii with the aid of a hand-lens or microscope.  Cyathea cunninghamii has hood-shaped indusia (the protective covering of the reproductive structures) and some of the frond scales are tipped with coloured spines.  Cyathea smithii has saucer-shaped indusia, and none of the bigger scales from the frond are tipped with coloured spines.  In C. medullaris, the indusia completely envelop the reproductive structures and the frond scales are fringed with marginal spines.  Additionally, the lower frond stalk of C. medullaris is smooth, whereas it is rough in C. cunninghamii.

Cyathea kermadecensis, which is endemic to New Zealand’s subtropical Kermadec Islands, is similar to C. cunninghamii.