July in the forest with Chris Horne and Barbara Mitcalfe
Cyathea medullaris, Mamaku, Black Tree Fern
You can easily identify our handsome mamaku, (black tree fern), by the thick black stalks of its fronds, and by the characteristic way the fronds arch upwards from the top of the trunk.
Mamaku is native to New Zealand and the Pacific islands from Fiji to Pitcairn. Common in low- land forest in the North Island, and in mostly coastal parts of the South Island, it is the most nu- merous tree fern in gullies in the Wellington region. On mamaku trunks, you may have noticed the distinctive hexagonal scars left by the fallen fronds. The largest of our eight species of tree fern, mamaku often emerges above the canopy, reaching to 20 m tall, with fronds to 5 m long.
Medullaris refers to the medulla, the spongy white pith in the centre of young mamaku fronds. In 1871, a colonist, O’Carroll, reported, “The poultices the native doctor uses are the convoluted tops of the mamaku, fern tree, boiled ... a strong drawing and very quick poultice.” Even today, this bush remedy is still used in some parts of New Zealand.
Possums browse all the green parts of mamaku fronds, leaving only the midribs and side ribs - the result looks like a fish skeleton! Mamaku scales are like flattened brown hairs which, seen under a lens, are so sharply serrated, it's no wonder we itch when they get into our clothing! The right place for a handful of these scales is in your fire-lighting kit, because they make effective tinder.