rough-barked and remarkably ancient

Size
Height: 400–700 cm
Lifespan
50–100 years
Diet
Grows in disturbed forest, forest margins, and regenerating bush. Requires bright, dappled light and well-drained soil. Tolerates a wide range of conditions including poor soil, exposed sites, and moderate frost. Spreads aggressively via underground runners to form large colonies.
Habitat
The whekī owns the disturbed ground, the forest margins, the slips and the scrub and the places where other ferns hesitate. It grows from Northland to Stewart Island, from sea level to 900 metres, and tolerates thin soil, harsh light, or fierce competition. It forms colonies.
Range
Found throughout the North and South Islands, Stewart Island, and the Chatham Islands in lowland and montane forests. Most common in disturbed forest, regenerating bush, and along roadsides from sea level to 900 metres elevation across New Zealand.
Endemism
Endemic
Main Threats
None significant as this species is abundant and secure throughout its range. It is one of New Zealand's most successful tree ferns, particularly common in regenerating bush and along roadsides. Possum browsing on the tender koru can affect local populations occasionally.
Population
Abundant and secure. The rough tree fern is one of New Zealand's most widespread and successful tree ferns, particularly common in regenerating bush, along roadsides, and in disturbed forest. It grows up to 7 metres tall and spreads aggressively via underground runners.
Conservation Status
Not Threatened
You have seen the whekī. You have probably walked through a whole forest of it without realising it was a single organism. That is the trick of the rough tree fern. It does not grow alone. It sends out underground runners, known as rhizomes, that pop up new trunks metres away from the parent. Over time, a single genetic individual can cover an area the size of a tennis court. Dozens of trunks rise from the soil like a small army. It is not just a fern. It is a collective. Roughness makes it special. The trunk is covered in stiff, persistent frond bases. These are the stumps of old leaves that never fall off. They stick out like bristles. Run your hand up the trunk and you will feel why it is called rough. Do not actually do this. It hurts. This is not a fern you hug. It has strong opinions about personal space. The fronds are dark green and leathery. They do not droop like the soft tree fern. They stand up, stiff and assertive. The undersides are paler but not silver. The koru, or fiddlehead, is covered in dark, bristly scales. Everything about the whekī says do not mess with me. It colonises. After a slip, after a fire, or after a logging operation, the whekī is often the first tree fern to appear. It sends out its runners and pops up new trunks. This creates a dense thicket that stabilises the soil and provides shelter for other plants. It is a pioneer. It is a nurse plant. It is the scrappy first responder of the forest. Reproduction by spores occurs, but its real superpower is the rhizome. A single trunk can send out a runner that travels five metres underground before surfacing as a new trunk. That new trunk sends out its own runners. And so on. Before you know it, the whole hillside is whekī. It provides habitat for insects, birds, and lizards. Its dense thickets offer shelter from wind and predators. Fallen fronds add organic matter to the soil. It is not the tallest fern. It is not the prettiest fern. It is the fern that gets things done. In a world of solitary tree ferns, such as the mamaku standing alone or the ponga keeping its distance, the whekī is the team player. It understands the power of numbers. It looks at a bare hillside and thinks it can fix that. And it does. Quietly, persistently, aggressively. The whekī is not planning a takeover. It has already taken over. You just have not noticed yet. No one told it otherwise.