the soil crust lichen of NZ's damp forest banks
- Size
- Width: 2–8 cm
- Lifespan
- 10–50 years
- Diet
- Grows on mossy banks, rotting logs, and bark of trees in damp, shaded forests. Requires clean air, stable surfaces, and high humidity. Tolerates shade and moisture but cannot survive prolonged drought.
- Habitat
- Grows on mossy banks, rotting logs, and bark of trees in damp, shaded forests. Forms small, leafy, moss-like lobes that tuck into mossy company.
- Range
- Found throughout the North and South Islands on mossy banks, rotting logs, and bark of trees in damp, shaded forests. Most common in the South Island's beech forests and the North Island's western ranges. Also found in temperate and cold regions worldwide.
- Endemism
- Native
- Main Threats
- None significant. This species is common and widespread in damp, shaded forests. Localised threats include forest clearance, air pollution, and climate change reducing forest floor humidity.
- Population
- Not Threatened. Psoroma lichen is common in damp, shaded forests throughout New Zealand, particularly in the South Island's beech forests and the North Island's western ranges. It grows on mossy banks, rotting logs, and the bark of native trees.
- Conservation Status
- Not Threatened
The one that looks like it is trying to be moss has a body that is small, leafy, and soft, with tiny, rounded lobes that form small patches on the mossy bank. The colour is pale greyish-green to brownish-green when dry, bright green when wet. The lobes are covered in tiny, fuzzy projections that give them a soft, mossy texture. It is the lichen of the mossy companion, the one that tucks itself into mossy company and hopes not to be noticed, the one that is a master of disguise.
What makes it special is the camouflage. Psoroma lichen is one of the best-hidden lichens in New Zealand. It grows among mosses, on mossy banks, in the soft, green carpet of the forest floor. Its colour and texture match the moss so well that you can walk right past it without seeing it. It is the lichen of the hidden patch, the one that blends in with its mossy neighbours, the one that you have to look closely to find.
The psoroma lichen is a foliose lichen, meaning it grows in flat, leafy lobes that are attached to the substrate at points but not completely stuck down. The lobes are small and rounded, often overlapping like the scales of a fish. The upper surface is covered in tiny, granular projections (granules) that give it a soft, fuzzy texture. Under a hand lens, the granules are visible, tiny bumps that make the surface look like velvet.
Biologically, the psoroma lichen is a partnership, a fungus and an alga living together. The fungus provides structure and protection. The alga provides food through photosynthesis. The psoroma lichen grows on mossy banks, rotting logs, and the bark of trees, preferring damp, shaded locations with high humidity.
To find psoroma lichen is to find the small, mossy patch on the bank. It is pale, soft, and hidden, a quiet companion to the moss. You have to look closely. You have to part the moss with your fingers. You have to know what you are looking for. It is the lichen of the mossy company, the one that tucks itself into the green carpet and hopes not to be noticed, the one that proves that the best way to survive is sometimes just to blend in.