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 Cyatheaceae 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 family have scales (if you look carefully at the picture of the mamaku koru (crook) on the left, 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, Sphaeropteris medullaris, is native to Aotearoa, Fiji, and parts of tropical 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, applied prinarily to a superficially similar Australian species, S. cooperi, has been acquired from Māori or Tahitian 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 Māori tradition this is one of the three children of Te Hāpuku who fled into the forest to escape the wrath of Tāwhaki, 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 patupaiaruhe, who in revenge made the mamaku's once rigid upward-pointing fronds droop downwards, as they do to this day.
The Mamaku 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. Throughout its range it occurs mostly at lower altutudes (below about 600 metres above sea level). It is somewhat frost-tender, especially when young (several well-established plants in Te Māra reo died as a result of an unusual series of frosts).
The mamaku is easily distinguished from the other
NZ members of the Cyathea family 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. 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. The fronds are up to 6m long, If you look at the scales on the fronds through a magnifying glass, you can see the spines along both margins, as in the greatly enlarged image on the right; this is unique to the mamaku among New Zealand tree ferns.
(The photograph shows a section of the underside of the frond measuring about 2 mm by 2.4 mm.)
The mamaku does not like being deprived of light, and if the canopy closes permanently above it in the forest the fern will languish and die. They grow at quite a fast pace (about a foot a year when young), and severed trunks will often revive and grow again if planted promptly. Young plants grown from spores can, however, be difficult to transplant successfully. Ocasionally branched specimens will be encountered, or some with angled trunks from branching or dodging neighbours. In favourable environments the fern may form groves.
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 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, kōrau, 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.
The significance of mamaku as a famine food is mentioned in poetry in Horomona Hapai of Ngati Porou's lament for the failure of crops (NM Vol. 2, pp. 308-9), where he urges people to "go inland to the food of Toi", the mamaku and the aruhe. This, and the mythical association of the mamaku with Tangaroa, atua of the sea, is perhaps why the mamaku is also mentioned in the karakia quoted in the page devoted to the ponga (Alsophila tricolor). Another reference in poetry is to the drooping fronds, perhaps but not necessarily a reference to the aftermath of their flight from Täwhaki, but certainly a metaphor for the sadness of the author, Te Ikakerengutu of Ngati Ruanui, after the death of his sons:
Etia nei au, e tama mā,
Ko te Atanga-a-Tāne
E tuoho i uta rā,
E piko nei me te mamaku
Ki āku tamariki.
[I am like, o sons,
The progeny of Tāne
That bend over the shore,
And droop there like the mamaku
Because of my children.]
[NM, Vol 2, pp. 366-7]
The "progeny of Tāne" are the trees of the forest and and also many of those of the seashore, like the pōhutukawa; the mamaku is one of the progeny of Tangaroa, through Te Hāpuku.
A note on botanical taxonomy
Shortly after Te Māra Reo Kawerongo #3 was sent out in January 2023, a decision was made that the NZPCN database should adopt a revised taxonomy for these plants following the publication of several comprehensive DNA and taxonomic studies overseas, most notably the 2016 report on fern classification by the Pteridophyte Phylogeny Group. The New Zealand tree ferns formerly placed under Cyathea were reassigned to the re-established genera Sphaeropteris (C. medullaris) and Alsophila (all the rest -- with the former C. dealbata being re-named A. tricolor). The other change affecting this page (in accordance with the classification recommended by the Pteridophyte Phylogeny Group) was to refer to the former Cyathea cooperi, an Australian tree fern which has been naturalized in Aotearoa and tropical Polynesia, as Sphaeropteris cooperi. The older designations are of course still the most commonly encountered in printed material, and they continue to be used by a significant number of botanists. Background notes on these changes will be found in Te Māra Reo Kawerongo 3 and 4.
