The wind never stops. The Subantarctic Webcap grows in its lee. Behind rocks. Beneath the Dracophyllum canopy. The mushroom is small. The cap is brown. Dark brown. Almost black when wet. The gills are pale at first. They darken to rust as the spores mature. The stem is fibrous. Tough. There is a cortina. A web of threads covering the young gills. The threads are white. Delicate. They tear as the cap expands. Remnants cling to the stem. The webcap dries in the wind. It rehydrates in the rain. It shrinks. It expands. It persists. The season is short. The fungus fruits in January. Sometimes February. Then the wind wins. The mushroom crumbles. The spores blow away. Threats are severe for a fungus with such a restricted range. Climate change tops the list. The subantarctic islands are warming faster than the global average. The peat soils are drying. The moss layer is thinning. Cortinarius subantarcticus needs dampness. Not wet. Damp. The mycelium lives in the top few centimetres of soil. When the soil dries, the mycelium dies. No fruiting. No spores. No replacement. The second threat is introduced mammals. Mice occur on Campbell Island. They eat fungal tissue. They eat Cortinarium fruit bodies. No one has filmed it. The inference is strong. The third threat is stochastic. The fungus exists in small populations. A single shipwreck introducing a competing fungus. A single fire from a discarded cigarette. A single landslide. The populations would not recover. Diet is mycorrhizal. Cortinarius subantarcticus forms a mutualism with subantarctic shrubs. Dracophyllum longifolium. Dracophyllum scoparium. Possibly other species in the same family. The fungus wraps around root tips. It penetrates between cells. The exchange happens underground. The shrub provides sugars. The fungus provides water and nutrients. Phosphorus is scarce on subantarctic islands. The fungus mines it from organic matter. It trades phosphorus for carbon. The shrub grows slowly. The fungus grows slowly. The partnership has lasted millennia. It may not survive the next century. Range is limited to the subantarctic islands of New Zealand. Confirmed records exist from Campbell Island and the Auckland Islands. Potential records from the Snares. None from the Antipodes. The fungus does not occur on mainland New Zealand. Not in Fiordland. Not on Stewart Island. The climate is wrong. Too warm. Too variable. The host shrubs are wrong. Dracophyllum on the mainland is different. The mycorrhizal compatibility is absent. The separation is complete. The islands have been isolated since the last glacial maximum. Twelve thousand years. The fungus has speciated. It cannot go back. Habitat is specific. Damp peaty soils under Dracophyllum scrub. The soil pH is acidic. 4.5 to 5.5. The organic matter content is high. Eighty percent. The fungus avoids open herbfield. It avoids exposed ridges. It avoids waterlogged depressions. The microsite is the key. Slight slope. Eastern aspect. Sheltered from the prevailing wind. The moss layer is intact. The humus layer is deep. The shrub roots are dense. The webcap fruits in these places. Sporadically. Unpredictably. A collector may search for a week and find nothing. The same site may produce twenty mushrooms the following year. The trigger is unknown. The temperature. The rainfall. The soil moisture. The fungus decides. It does not explain its choices.