Unearthing the rich past of New Zealand's black tree fern

Look at this beautiful New Zealand specimen! These lush black tree fern Cyathea medullaris can be found throughout our zoo grounds, providing ample canopy cover for our native birds.

Most commonly found in the humid lowland forests of the North Island, these stunning rākau (tree) fern are also distributed on several of New Zealand’s outlying islands such as Stewart Island (Rakiura) and the Chatham Islands. Although these ferns can be found in the wetter areas of the South Island, they are noticeably absent from the Canterbury and Otago regions.

Interestingly, as much as 40% of New Zealand’s ferns are endemic, meaning they are naturally found nowhere else on earth, though these twenty-meter high ferns are common across Polynesia, in places like Fiji, the Marquesas Islands, Tahiti and Pitcairn Island.

If we break down its scientific name, Cyathea comes from the Greek word kyatheion meaning 'little cup' which refers to the shape of the indusium - a membrane that grows underneath the surfaces of fern leaves that protect the developing sporangia, while medullaris denotes the pithy (and edible!) white tissue inside the trunk.

New Zealand’s largest fern species, Cyathea medullaris has a black-stalked trunk covered with hexagonal stripes or depressions left behind from fallen fronds. As kiwis know well, the fern frond and koru is an important part of our cultural heritage as a symbol that unifies us as a nation - worn on the jerseys of our greatest sporting teams, our currency, and everything in between.

Also known as mamaku, katātā or kōrau in Te Reo, Māori pūrākau (legend) tells of the children of Te Hapuku who swiftly fled to the seas and forests to escape the wrath of Tawhaki, who planned to avenge the death of his father. While many of his offspring became whales and other great fish, one of the children became the mamaku or ‘fish of the forest’, whose scales can still be seen on the surface of the trunk today.

This useful fern also holds a special place in Māori culture for its uses as rongoā (medicine) to treat a number of different maladies; mixed with hot water it can be used as a poultice for treating sore eyes and inflammation. Gum from the tree’s trunk can be used to treat gastro-intestinal complaints and young shoots (pītau) can be boiled and drunk as a liquid to assist women in recovering after a difficult labour.  It is also effective at relieving the effects of sunburn or any abrasions to the skin, like eczema, blisters or bites.

Known as a ‘famine food’ for Māori when crops failed, new shoots offered great nutritional value when times were tough and could be made into a relish, a soup or baked in a hangi – with a similar taste to turnips or marrow. Māori poems and literature also refer to the mamaku’s drooping ferns as symbols of grief.

Native ferns look stunning in the home garden and mamaku are easy to transplant as young ferns and become quite hardy once established, this plant is also known for holding the earth together after a landslide – a handy bonus!

Our New Zealand sanctuary, Te Wao Nui, is a haven for our native plants – so make sure to visit with your family. 

Stay tuned for the next blog in this series and if you have any recommendations on plants we should cover or questions for our horticulture experts, flick us an email!