Plant profiles > Cyathea

Family : Cyathaceae

Tree ferns have become entwined with our identity as New Zealanders; a fact that is most emphatically borne out in the use of the silver fern as an emblem for our national sporting teams (as well as constituting a de facto national flag on occasions). It is easy to understand how this has come about, when one views many of our tree ferns in the landscape.

They have easily read, yet complex, forms that stamp a strong character on the areas that they inhabit; but more importantly, they are just so different from their neighbours. As Michael Shepherd has stated to me on several occasions, landscape compositions are made up of 'field' (the broad, intergrading mantle of a view) and 'points' (that break forth from, or disrupt, this mantle). When thought of in this manner, we can recognise tree ferns as distinctive 'points', that project sharply forwards in our perception of the forest (in both real and symbolic terms1).

It is also possible that our veneration for the tree fern partially derives from the sensibilities of the people that effected New Zealand's colonisation by the British Empire over the course of the 19th Century. In light of the Victorian craze for ferns, these stately ferns were likely candidates for national symbols - becoming entrenched within our national consciousness when modern New Zealand was at a formative stage.

In New Zealand, tree ferns fall into one of two genera, Cyathea and Dicksonia. Although all of our tree ferns thrive best in moist, sheltered sites, Cyathea spp. are particularly reliant on such stable conditions, due in part to their softer fronds. The famous silver fern is a member of Cyathea (C. dealbata), as is the towering black mamaku (C. medullaris), the largest of our tree ferns.

In all, there are seven New Zealand species of Cyathea (although two of these are confined to the Kermadec Islands), in a genus that comprises several hundred species. The name, Cyathea, is derived from a Greek term for a wine ladle, kyathos2. It refers to the cup-like flap that covers the spore-producing structures (sori) that one sees speckled on the underside of fern leaves.

Cyathea medullaris
Mamaku; Black mamaku

This majestic plant is impressive on several counts; from its large umbrellas of vibrant green foliage to its blackish trunk, and the grand scale that it attains (it grows up to 20m tall). Due to its considerable size, mamaku is a conspicuous feature of New Zealand's lowland forests, except on the dry eastern side of the South Island, where it is almost absent.

For the purposes of cultivation, Cyathea medullaris is the most adaptable member of the genus, as it will handle an open position and a relatively high level of wind (a degree of tolerance that is logical in plants that emerge from the surrounding canopy of bush). Although they can grow in a sunny aspect from an early age, they are ideally planted in a spot where they receive shade on their roots. During establishment, they may require watering in dry periods, especially if vigorous growth is desired.

A distinctive feature of mamaku is the presence of hexagonal scars, where the fronds become detached from the trunk. These combine to form a regular pattern on the trunk.

In describing the use of mamaku as a food supply for Māori, the ethnographer Elsdon Best stated that "it was often useful to travellers, and to others in times of scarcity"3. Best recounted how the inner part of the trunk (called the pith) was used, although the lower parts of the fronds' stems were also purported to be eaten. Best pointed out that the pith was only utilised from the upper parts of the trunk. Extended steaming (in hāngi) helped to turn the slimy base material into an edible form, that was (by all accounts) fairly tasty.

The specific epithet, medullaris, is in fact a reference to this edible inner part of the trunk2. It is derived from the Latin word, medulla - which was originally a term for 'marrow' (as in bone marrow) - and came to be applied (in botanical terms) to the pith.

 


Footnotes

  1. Michael Shepherd makes the point that our mode of engaging with the world is that we scan. We are perpetual information collectors. Such 'points' serve not only to order a view. They make scenes more intimate, for the wilderness of the 'field' is punctuated by these individuals, which become a locus for our attention.
  2. As stated within 'Meanings and origins of botanical names of New Zealand plants' (Taylor, M. 2002. Auckland Botanical Society Bulletin 26.).
  3. Within 'Forest Lore of the Māori' (Best, E. 1977 (Reprint). Wellington : E.C. Keating, Government Printer).