It is not rare. It is seasonal. Walk through the Otago high country in autumn. February or March. The tussock is brown. The wind is cold. Look down. The puffballs are there. White. Round. The size of marbles. Larger. Some reach the size of golf balls. They grow in clusters. Five. Ten. Twenty. Each one attached to the soil by a thin cord. The surface is warted. Covered in tiny pyramids. Touch one. It is firm. Leathery. Press harder. The skin indents. It does not break. The puffball is not ready. Inside, the flesh is white. Solid. Immature. Wait. A week. Two weeks. The flesh turns yellow. Then olive. Then brown. The spores form. The skin dries. A hole opens at the top. Rain hits the puffball. Spores puff out. A cloud. Brown. Dusty. The wind takes them. The puffball collapses. It is done. The Tussock Puffball is saprotrophic. It decomposes organic matter in high country soils. Tussock roots. Dead grass leaves. Sheep dung. The fungus lives in the topsoil. The mycelium spreads through the root zone. It fruits when conditions are right. Autumn rain. Cool nights. The soil temperature below fifteen degrees. The puffballs emerge within days. They mature within weeks. The timing is precise. Too early and the spores are not ready. Too late and the frost kills them. The fungus solves this by fruiting in autumn. The frost comes in late autumn. The puffballs finish before it arrives. Habitat is restricted to South Island high country tussock grasslands. The species occurs from the Kaikoura Ranges south to Otago. It follows the distribution of snow tussock (Chionochloa species). The fungus grows on exposed mineral soil. Between tussocks. On eroded slopes. On the edges of stock tracks. It avoids dense vegetation. It avoids deep litter. It needs light. It needs disturbance. The same disturbance that damages tussock creates habitat for the puffball. The relationship is complicated. The fungus does not benefit from overgrazing. It benefits from moderate grazing. The hoof prints create bare soil. The puffball colonises the bare soil. Too many hoof prints and the soil compacts. The mycelium dies. The balance is narrow. Range across New Zealand is limited to the South Island high country. Confirmed populations exist in the Kaikoura Ranges, the Craigieburn Range, the Otago high country around Naseby and the Rock and Pillar Range, and the Mackenzie Basin. A single North Island record exists from the Central Plateau. It has not been relocated. The species may be absent from the North Island. The climate is different. Warmer. Wetter. Less seasonal. The tussock is different. Snow tussock in the North Island is Chionochloa rubra. The fungus may not recognise it. The relationship may require a different host. The mycology is uncertain. The puffball does not explain itself. Threats include grazing intensification, conversion of tussock to exotic pasture, and climate change. Overgrazing compacts soil. Compacted soil does not host the puffball. The mycelium cannot penetrate. The fruit bodies cannot emerge. Fertiliser application changes soil chemistry. The fungus is adapted to low-nutrient conditions. Added phosphorus alters the microbial community. The puffball loses. Exotic grasses replace tussock. The substrate changes. The fungus cannot adapt. Climate change brings drier summers. The soil dries. The mycelium dies. The tussock persists. The puffball does not.