Cyathea medullaris

mamaku, black tree fern

Cyathea medullaris occurs throughout the lowlands and mid-altitudes of the North Island, and in the north and west of the South Island, where it is usually coastal.  It prefers warm, wet areas, and is a common coloniser of hillside slips.  Cyathea medullaris is also recognised from several Pacific Islands, including Fiji.

It is recognised by its thick, black frond stems, and long, arching fronds.  It is New Zealand’s tallest tree fern, reaching c. 20 m.

Although not closely related, Cyathea cunninghamii can be confused with C. medullaris.  Cyathea cunninghamii has shorter fronds and thinner frond stems, and usually a more slender trunk.  Microscopically, the indusia (a protective covering) of C. medullaris completely envelop the reproductive structures and the frond scales are fringed with marginal spines.  By contrast, C. cunninghamii has saucer-shaped indusia and the frond scales are not marginally fringed, although stellate (star-shaped) hairs are abundant.

Traditional uses: The pith of the trunk, the bases of the stems of the fronds, and the uncurling new fronds can be eaten (Crowe, A Field Guide to the Native Edible Plants of New Zealand, Penguin).  It was also used to treat skin problems, sore eyes, parasites, and diarrhoea (Brooker et al., 2002, New Zealand Medicinal Plants, Reed).