dots the rough bark of damp forest trees

Size
Width: 2–8 cm
Lifespan
10–50 years
Diet
Photosynthetic symbiosis. Requires clean air, stable bark surfaces, and high humidity in damp, shaded forests.
Habitat
Grows on bark of trees, rocks, and wood in damp, shaded forests. Found in moist, sheltered locations where the bark is rough.
Range
Found throughout the North and South Islands on bark of trees, rocks, and wood. Most common in beech forests and western ranges.
Endemism
Native
Main Threats
None significant. This species is common in damp, shaded forests. Localised threats include forest clearance, air pollution, and climate change.
Population
Not Threatened. Thelotrema lichen is common in damp, shaded forests throughout New Zealand, particularly on native trees in undisturbed locations.
Conservation Status
Not Threatened
Human Risk
harmless
Handling Note
crustose lichen, safe to handle
Conservation Note
Native lichen; not assessed by NZTCS as lichens are generally outside the scope of current threat classifications.
Te Ao Māori
No recorded Māori name distinguishes the thelotrema lichen from other lichens. Lichens were generally called pūkohu (mosses and lichens) or pukorokoro (crustose lichens). The tiny, eye-like structures on the bark would have been noticed. They looked like the eyes of a fish, like the spots on a bird, like the gaze of the forest, but no distinct name survives. The thelotrema lichen was sometimes used as a dye. The pale pigment could be extracted and used to colour fibres, though it was not as vibrant as other lichens.
You have to look closely. Thelotrema lepadinum looks like it is watching you. Its body is a thin, crusty layer. It grows on the surface of the bark. Forming a pale greyish-white to off-white patch. The crust is smooth and even. Like a coat of pale paint. But scattered across the surface are tiny, delicate openings. The fruiting bodies, or apothecia. They look like miniature eyes. Each opening is ringed with a raised, pale rim. The centre is dark. Like a pupil. It is the lichen of the watching eye. The one that seems to stare back at you from the bark. What makes it special is the eyes. Thelotrema lichen is one of the most distinctive lichens in New Zealand. Its fruiting bodies are not flat discs like many other crustose lichens. They are raised, ringed structures with a central opening. Like tiny volcanoes or miniature eyes. The rim is pale and often slightly crenulated. Wavy. The centre is dark. Giving the whole structure the appearance of a tiny eye staring out from the bark. It is the lichen of the watching gaze. The one that seems to follow you as you move. The one that makes you feel observed. The thelotrema lichen is a crustose lichen. It grows flat on the bark or rock. Like a crust of paint. Rather than upright or leafy. Its body is a smooth, continuous crust. Often forming circular patches or irregular stains. The apothecia are raised, ringed structures with a central opening. Giving them a unique, eye-like appearance. Under a hand lens, the apothecia are beautiful. Perfect circles with a dark centre and a pale, wavy rim. Biologically, the thelotrema lichen is a partnership. A fungus and an alga living together. The fungus provides structure and protection. The alga provides food through photosynthesis. The apothecia are the spore-producing structures. Releasing spores into the air through the central opening. To find thelotrema lichen is to find the tiny eyes on the bark. It is pale, crusty, and watching. A living gaze on the tree. You have to look closely. You have to bring your face close to the bark. You have to let the lichen stare back at you. It is the lichen of the watching eye. The one with tiny, ringed openings like tiny eyes staring from the bark. The one that proves that the forest is watching you back. No recorded Māori name distinguishes the thelotrema lichen from other lichens. Lichens were generally called pūkohu or pukorokoro. The tiny, eye-like structures on the bark would have been noticed. They looked like the eyes of a fish. Like the spots on a bird. Like the gaze of the forest. No distinct name survives. The thelotrema lichen was sometimes used as a dye. The pale pigment could be extracted. Used to colour fibres. Though it was not as vibrant as other lichens.