Sedges are not showy like flowers or mighty like trees. They are grasses that are not quite grasses – triangular stems, spiky seed heads, leaves that cut your fingers if you pull too hard. They grow in the places where nothing else will grow – swamps, sand dunes, mountainsides. They are the quiet workers of the plant world. And there was once a sedge that grew on the highest, steepest, most unstable ground in New Zealand – the alpine scree slope. Its leaves hung down the rock face like a green waterfall. Its roots held the shifting stones together. It was the giant alpine hanging sedge, and it is gone. The alpine scree slope is a dangerous place – stones shift with every footstep, soil is almost non-existent, the wind never stops, and winter brings snow and ice. Most plants cannot survive here. But the giant hanging sedge had evolved a perfect solution. Its roots spread wide and deep, grabbing onto stones, binding them together. Its long, cascading leaves absorbed the force of wind and rain. Its tough, fibrous blades resisted tearing. It was a living net, draped over the mountain, holding everything in place. It built the scree. Not literally – the rocks came from the mountains – but it stabilised them. A slope covered in hanging sedge was a slope that stayed put. Seeds could germinate in the shelter of its leaves. Insects could hide in its roots. Lizards could bask on the stones it held. It was the foundation species of the alpine scree, the plant that made the ecosystem possible. It reproduced by seed and by division – its root system could send up new shoots, forming large clonal mats that could persist for decades or centuries. It was slow-growing, investing its energy in deep roots and tough leaves rather than rapid reproduction. That strategy works when the slope is stable. It fails when the grazers arrive. Introduced grazing mammals destroyed it. Europeans brought possums, deer, goats, chamois, and thar to New Zealand. These animals love alpine plants. They ate the hanging sedge – its long, tender leaves, its nutritious roots, its seed heads. They trampled the scree, dislodging stones, breaking up the root mats. A single deer can destroy decades of growth in a single meal. The erosion that followed was catastrophic. Without the sedge's roots to hold them, the scree slopes began to slip. The stones tumbled downhill, taking what remained of the sedge with them. The mountain stripped bare. By the 1930s, it was gone. The last specimens were collected by a botanist who had no idea he was holding the final individual. He pressed them, labelled them, put them in a drawer. And the mountain fell silent. The smaller sedges survived. They are tougher, more adaptable, able to grow in the cracks between stones. Some still hang on in remote alpine valleys. But the giant alpine hanging sedge is extinct. A few pressed specimens in a herbarium, a few fragments of root in a scree deposit, and the memory of a plant that used to drape the mountain like a green waterfall. We brought the grazers. Then we wondered why the mountain fell apart.