Cyathea medullaris


Cyathea: From the Greek kyatheion 'little cup', referring to the shape of the indusium
medullaris: pithy (trunk)

Common Name(s)

black tree fern, mamaku, black mamaku

Current Conservation Status

2012 - Not Threatened

Conservation status of New Zealand indigenous vascular plants, 2012
The conservation status of all known New Zealand vascular plant taxa at the rank of species and below were reassessed in 2012 using the New Zealand Threat Classification System (NZTCS). This report includes a statistical summary and brief notes on changes since 2009 and replaces all previous NZTCS lists for vascular plants. Authors: Peter J. de Lange, Jeremy R. Rolfe, Paul D. Champion, Shannel P. Courtney, Peter B. Heenan, John W. Barkla, Ewen K. Cameron, David A. Norton and Rodney A. Hitchmough. File size: 792KB

Previous Conservation Status

2009 - Not Threatened
2004 - Not Threatened


Cyathea medullaris (G. Forst.) Sw.



Brief Description

Large tree fern with black-stalked leaves to 5m long. Trunk with obvious scars from old leaves, to 20m tall. Leaf stems covered in small scales that have a spiny edge (lens needed). Sporangia arranged in small round capsules underneath leaves.

Flora Category

Vascular - Native

NVS Species Code


The National Vegetation Survey (NVS) Databank is a physical archive and electronic databank containing records of over 94,000 vegetation survey plots - including data from over 19,000 permanent plots. NVS maintains a standard set of species code abbreviations that correspond to standard scientific plant names from the Ngä Tipu o Aotearoa - New Zealand Plants database.

Structural Class



Sphaeropteris medullaris (G.Forst.) Bernh.; Cyathea medullaris var. polyneuron (Colenso) C.Chr.; Cyathea medullaris var. integra Hook.; Cyathea polyneuron Colenso; Polypodium medullare G.Forst.;


Indigenous. Occurring form the Three Kings Islands south to Stewart and the main Chatham Islands. Uncommon in the drier eastern portion of the South Island, and apparently absent from Canterbury and Otago.


Common in lowland forest throughout the North Island. Primarily in wetter coastal areas of the South Island.


Tree fern up to 20 m tall. Trunk black covered with hexagonal stipe bases. Stipes thick, black, harsh to touch, covered in black scales. Scales with marginal spines. Fronds up to 5 m long, arching upwards from crown, 3-pinnate, leathery, dead fronds falling (except in very young plants). Longest primary pinnae 0.4-1 m long, undersurfaces bearing scales with marginal spines. Indusia completely covering sori at maturity, splitting irregularly.

Similar Taxa

Easily recognised by trunk with its distinctive hexagonal stipe scars and by the scales which possess marginal spines.


None (spore bearing)

Flower Colours

No Flowers


None (spore bearing)

Propagation Technique

Can be grown from fresh spores (but slow). Young plants transplant easily and freshly felled trunks will usually resprout if planted and carefully watered. Easy, once established in a variety of conditions. Should not be removed from the wild unless with landowner permission.


Not Threatened.

Chromosome No.

2n = 138

Endemic Taxon


Endemic Genus


Endemic Family


Life Cycle and Dispersal

Minute spores are wind dispersed (Thorsen et al., 2009).

Where To Buy

Commonly cultivated. Not as freely available from nurseries as other tree ferns because it is slow from spores and sporelings are notorious for failing following transplants.


Fact sheet prepared for NZPCN by P.J. de Lange March 2004. Description adapted from Brownsey & Smith-Dodsworth (2000).

References and further reading

Brownsey, P.J.; Smith-Dodsworth, J.C. 2000: New Zealand Ferns and Allied Plants. Auckland, David Bateman

Esler, W.R. 1976. Succession of fronds of mamaku (cyathea medullaris). Wellington Botanical Society Bulletin 39: 41-43


This page last updated on 30 Dec 2014