tallest fern in the southern world

Size
Height: 1000–2000 cm
Lifespan
100–200 years
Diet
Grows in damp, rich soils in gullies and lowland forests. Requires high humidity, consistent moisture, and protection from strong winds. Thrives in shaded understorey but will push up through the canopy to reach light for optimal growth and frond development.
Habitat
The mamaku dominates the damp gullies, lowland forests, and stream banks of New Zealand. From Northland to Stewart Island, wherever the soil is rich and the air is wet. It is a tree fern of the shadows and the edges, pushing up through the canopy of broadleaf and podocarp.
Range
Found throughout the North and South Islands, Stewart Island, and the Chatham Islands in lowland and montane forests. Most common in damp gullies and stream banks from sea level to 600 metres, from Northland to Southland, particularly abundant in the West Coast.
Endemism
Endemic
Main Threats
None significant as this species is abundant and secure throughout its range. Local populations can be affected by possum browsing, as possums eat the tender koru, and by forest clearance. However, the species is widespread and common, with no major conservation concerns.
Population
Abundant and secure throughout its range, though local populations can be affected by forest clearance and possum browsing. Possums love the tender koru. The mamaku is the tallest of New Zealand's tree ferns, reaching 20 metres in good conditions. Not threatened. Not worried. Just growing.
Conservation Status
Not Threatened
Walking through a lowland forest, the light is green and dappled. The air smells of damp earth and rotting leaves. You look up. And there it is. A black column rising twenty metres into the canopy. As straight as a pole. As dark as charcoal. With a crown of fronds that unfurl like a green explosion at the top. That is the mamaku. The black tree fern. And it looks exactly like something that watched the moa walk by and thought amateurs. The scale is imposing. The presence is undeniable. The trunk makes it special. Other tree ferns have trunks covered in the stumps of old fronds. Rough, fibrous, brown. The mamaku has a smooth, black, glossy trunk that gleams in the wet. It looks like polished ebony. It feels like cool marble. It is, without question, the most distinguished trunk in the fern world. The fronds are enormous. Up to five metres long. They arch out from the crown like a green umbrella. The undersides are paler than the silver fern, but not quite silver. The koru, or fiddlehead, is massive. Covered in black scales. Looking like something that should be in a dinosaur's mouth. The visual impact is total. It grows. Slowly. A mamaku can live for centuries. It adds a few centimetres of trunk each year. It sends up new fronds from its crown. Each one unfurls from a tight spiral. Reproduction occurs by spores. The fertile fronds bear clusters of sporangia on their undersides. It provides habitat for epiphytes. Ferns, orchids, mosses cling to its black trunk. It offers shelter for birds and insects. And it feeds the possums. Unfortunately. The koru of the mamaku is a favourite target for introduced possums. They climb the trunk. They eat the tender, unfurling fronds. A possum can kill a mamaku by eating its crown. That is not the mamaku's fault. That is ours. The vulnerability is acute. But the mamaku persists. You can see it all over the North Island. In the bush of the South Island. On the offshore islands where possums have not yet reached. It stands there, black and straight. Looking down at the ferns and the shrubs and the people walking past. It seems to say: I was here before you. I will be here after you. Do not expect me to be impressed. The attitude is justified. The longevity supports it. It is not showy. It is not silver. It is just black, and tall, and ancient. And that is enough. No one told it otherwise.