Hikers miss it. Not because it is rare. Because it grows low to the ground in remote alpine areas. The alpine water fern clings to rocky stream beds and seepages where water flows cold and fast. Its fronds are small and narrow, coloured dark green, resistant to freezing temperatures. This hardy appearance helps it survive in harsh high-country environments. The species inhabits alpine streams and seepages in high country throughout the South Island. It prefers cold fast-flowing water with rocky substrate. Unlike lowland ferns that require warmth, this species has adapted to freezing conditions. Fronds are narrow and lance-shaped, growing in tight clumps from rock crevices. Spores are produced on the underside of fertile fronds in continuous lines along the midrib. These spores are released into cold mountain air, settling on nearby wet rock surfaces where moisture allows germination. Diet consists of nutrients obtained through photosynthesis and absorption from cold water and rock weathering. The fern does not consume organic matter directly but rather extracts minerals from fast-flowing alpine streams. This cryophilic lifestyle allows it to thrive in nutrient-poor high-altitude environments where other plants cannot establish. Classified as Not Threatened, alpine water fern remains widespread throughout South Island alpine regions. Populations are stable in suitable habitat. However the species is sensitive to habitat disturbance. When alpine streams are diverted or modified for hydroelectric power, populations decline rapidly. Its presence signals intact alpine hydrological regimes and suitable moisture levels. Conservation efforts focus on protecting remaining alpine stream habitats from development and maintaining natural flow regimes.