It does not grow in the north. Not because it cannot survive there. Because it evolved in isolation in southern coastal regions, separated from northern populations by kilometres of seawater and different climate conditions. Lyall's spleenwort exists only in these southern outcrops, a product of geographic isolation and evolutionary divergence. The species inhabits coastal rocks and cliffs in southern New Zealand. It prefers exposed sites with salt spray and minimal soil. Unlike mainland ferns that require sheltered conditions, this species has adapted to harsh maritime environments. Fronds are thick and leathery, coloured dark green, with a waxy coating that repels salt. Spores are produced on the underside of fertile fronds in linear sori. These spores are released into the air, drifting on strong winds along the coastline. Diet consists of nutrients obtained through photosynthesis and absorption from sea spray and rock weathering. The fern does not consume organic matter directly but rather extracts minerals from salt water and rock surfaces. This halophytic lifestyle allows it to thrive in nutrient-poor coastal environments where other plants cannot establish. Classified as Not Threatened, Lyall's spleenwort remains widespread throughout southern coastal New Zealand. Populations are stable in suitable rocky habitat. However the species is sensitive to habitat disturbance. When coastal rocks are modified for construction or recreation, populations decline rapidly. Its presence signals intact geological features and suitable maritime conditions. Conservation efforts focus on protecting remaining coastal outcrops from development and maintaining natural hydrological regimes.