cabbage tree of the high cold slopes

Size
Height: 4–6 m
Lifespan
50–100 years
Diet
Herbivorous – absorbed nutrients through extensive root system gripping thin mountain soil. A cabbage tree built for the cold – stunted, thick-trunked, with leaves that could withstand snow and ice. Grew slowly, a few centimetres each year, its roots gripping the thin mountain soil. The last tree before the alpine zone, a survivor of frost and wind.
Habitat
High slopes, rocky outcrops, and subalpine scrublands of the Southern Alps and volcanic peaks of the central North Island. A cabbage tree built for the cold – stunted, thick-trunked, with leaves that could withstand snow and ice. Grew slowly, a few centimetres each year, its roots gripping the thin mountain soil. The last tree before the alpine zone, a survivor of frost and wind.
Range
Found on high slopes, rocky outcrops, and subalpine scrublands of the Southern Alps and volcanic peaks of the central North Island. Described from subfossil remains – preserved wood, leaves, and pollen – found in alpine deposits and early naturalist accounts. Last reliably recorded in the 1890s.
Endemism
Endemic
Main Threats
Climate warming was the primary threat, reducing its alpine habitat. Also threatened by browsing by introduced goats and chamois, and fire. Last reliably recorded in the 1890s. A few fragments of wood remain in museum collections – their growth rings tight, their fibre dense, their mountain slopes silent.
Population
A distinct alpine species of cabbage tree, related to the living tī kōuka (Cordyline australis) and the mountain cabbage tree (Cordyline indivisa). Estimated height 4–6 metres – shorter than its lowland relatives but with a thicker, more gnarled trunk. Trunk diameter 40–60 centimetres. Its leaves were shorter, broader, and tougher than any living Cordyline, adapted to high winds and heavy snow. Last reliably recorded in the 1890s, gone by the 1920s.
Conservation Status
Extinct
The cabbage tree – tī kōuka – is that iconic, spiky-leaved tree of the New Zealand landscape, a survivor of swamps and droughts, a pioneer of disturbed ground. But there was once a cabbage tree that lived where no cabbage tree grows today – the high mountains, the rocky slopes above the bush line, the places where snow lingers and the wind never stops. It was shorter, stouter, tougher than any living cabbage tree. Its trunk was thick and gnarled, its leaves were broad and tough, its roots gripped the thin mountain soil. It was the alpine cabbage tree, and it is gone. Extreme cold tolerance and slow growth made it special. A mountain cabbage tree might take 200 years to reach 5 metres – a lifetime of slow, patient growth. Its wood was incredibly dense, resistant to rot and frost damage. Its leaves were covered in a thick waxy cuticle, reducing water loss in the dry mountain air. It could survive snow loads that would snap a lowland cabbage tree. It marked the treeline. In the mountains, the treeline is not a sharp line but a transition zone – tall trees below, stunted trees above, then scrub, then alpine herbs. The alpine cabbage tree was the dominant tree of this transition zone, the last tree before the open alpine zone. It provided shelter for smaller plants, habitat for birds and insects, and stability for the mountain slope. Its flowers – large, white, sweet-scented – bloomed in summer, feeding native bees and moths. Its berries fed the birds. Its fallen leaves added organic matter to the thin mountain soil. It flowered prolifically in good years, producing masses of berries. The seeds were dispersed by birds – the tūī, the kākā, the bellbird – that carried them up and down the mountain. It also spread by root suckers, forming clonal groves that could persist for centuries. That strategy works when the climate is stable. It fails when the climate shifts and the grazers arrive. Climate warming and introduced grazers destroyed it. At the end of the last ice age, the climate warmed. The alpine cabbage tree, adapted to cold, found its habitat shrinking. The treeline moved up the mountain – but there is only so far up you can go. Eventually, there was no mountain left. Then the goats arrived. European settlers introduced goats, chamois, and thar to the mountains. These animals love cabbage trees. They ate the leaves, stripped the bark, trampled the seedlings. A slow-growing tree that takes decades to reach maturity cannot survive annual browsing. Fire was the final blow. Hunters burned the subalpine scrub to clear hunting grounds. The alpine cabbage tree, with its dense, fibrous wood, burned readily. The old trees, already stressed by warming and browsing, could not regenerate after fire. By the 1920s, it was gone. The last trees were probably eaten by a goat or burned by a hunter's fire. No one knew they were the last. The lowland cabbage tree survived. Tī kōuka is more adaptable, able to grow in a range of conditions. It is the survivor, the pioneer, the tree of the valleys. But the alpine cabbage tree is extinct. A few fragments of wood in a museum drawer, a few pollen grains in a mountain bog, and the memory of a tree that used to mark the treeline. The climate warmed. The goats came. Then we wondered why the mountain felt so bare.