There are two sets of tree ferns in the New Zealand flora, the members of the Cyathea family like the mamaku and the ponga, and the members of the Dicksonia family, like the wheki and wheki-ponga. The Cyatheae generally have larger and more graceful fronds, but the families are also easily distinguished by looking at the stipes (the central supports for the fronds); those of the Cyathea species have scales (if you look carefully at the picture of the mamaku koru (crook) opposite, and the photo of the unfolding wheki [Dicksonia squarrosa] frond on the page for that fern, you can see the scales and hairs respectively distributed along the stipes).

The (New Zealand) mamaku, Cyathea medullaris, is native to Aotearoa, Fiji, and parts of Polynesia, although because it is a strikingly handsome tree fern it is now widely grown around the world. It is likely that the Rarotongan cognate for this name has been acquired from Mäori rather than directly inherited from the original name, although the latter probably originated in Tahiti (where the mamaku does grow natively) or the Marquesas. There is no doubt, however, about the antiquity of the Hawai'ian name!

In Mäori tradition this is one of the three children of Te Häpuku who fled into the forest to escape the wrath of Täwhaki, and took the form of tree ferns. Murdoch Riley in his Herbal gives an interesting addendum to this event. Apparently the mamaku later offended the malignant forest elves, who in revenge made the mamaku's once rigid upward-pointing fronds droop downwards, as they do to this day.

The tree itself is tall and imposing, reaching a height of up to 20 metres in favourable conditions, and often towering above the surrounding vegetation. It is found throughout New Zealand, including the Chatham and Three Kings Islands and Stewart Island, but is more common in warmer areas with plenty of moisture. It is easily distinguished from the other NZ species of Cyathea by the absence of old fronds clinging to the trunk, and the hexagonal scars left on the trunk by the old fronds as they fall away.

There is a wealth of information about traditional uses of the mamaku and lore connected with it in Murdoch Riley's Herbal. The mucilage from the sap, and also the pith from the upper part of the trunk and squeezed from the young leaves were widely used as poultices for a variety of skin conditions, and also to give relief to fatigued limbs. I can personally testify to the almost magical efficacy of the sap from the stipes of new fronds as a remedy for sunburn. It also apparently works as a treatment for boils, and also as a coagulant to help stem bleeding from the skin.

The gum oozing from a bruised trunk when solidified was apparently chewed as a remedy for diarrhoea, and prepared in a different way could also be a laxitive.

Baked in a hangi, the pith from the upper part of the mamaku trunk and also from the stipes of young fronds was eaten both as a famine food and as a special relish at feasts. It was also thought to be highly beneficial to the child in the womb when eaten by pregnant women, and to assist women to recover after a difficult childbirth. (Restraint had to be used where the pith from the trunk was involved, as the whole tree has to be destroyed to obtain it. Andrew Crowe says that the flavour was improved by bleeding the trunk by bruising it, to remove the bitter flavour caused by the sap.)

Various observers have commented on the taste of baked mamaku, mostly favourably and likening it to turnip or marrow. Interestingly, one of the alternative names for this fern, körau, has long been applied to a variety of turnip (introduced to Aotearoa by Captain Cook). One early account likened the taste favourably to that of sago, which is prepared from the pith of a species of palm. Andrew Crowe found the dried pith of the stipes (which can be gathered without demolishing the tree) very pleasant to eat when baked or as an ingredient in soup.