crusts the pale limestone outcrops

Size
Width: 5–20 cm
Lifespan
20–100 years
Diet
Grows on limestone and calcareous rocks in sunny, exposed locations. Requires alkaline substrate, clean air, and stable rock surfaces. Tolerates sun, wind, and drought once established.
Habitat
Grows on limestone and calcareous rocks throughout New Zealand. A creature of the chalky stone, the lime-rich rock, the places where the stone is soft and the surface is pale. Found from sea level to the montane zone, particularly on limestone outcrops, old mortar, and calcareous rock faces.
Range
Found throughout the North and South Islands on limestone and calcareous rocks. Most common in the South Island's limestone regions and the North Island's east coast. Also found in temperate regions worldwide.
Endemism
Native
Main Threats
None significant. This species is common and widespread on calcareous rocks. Localised threats include quarrying of limestone outcrops, removal of stone walls, and air pollution.
Population
Not Threatened. Aspicilia crust lichen is common on limestone and calcareous rocks throughout New Zealand, particularly in the South Island's limestone regions and the North Island's east coast. It grows on natural rock outcrops and on man-made structures like old stone walls and mortar.
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 aspicilia crust lichen from other lichens. Lichens were generally called pūkohu (mosses and lichens) or pukorokoro (crustose lichens). The chalky, pale patches on the limestone would have been noticed. They looked like the breath of the rock. Like the mark of age. But no distinct name survives. The aspicilia crust 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.
Stone exhales here. The aspicilia crust lichen looks like a pale stain on the limestone. Its body is a thick, crusty layer. It grows on the surface of the rock. Forming a pale grey to off-white patch. The colour is a dull, chalky white. Sometimes with a hint of green or brown. The surface is often cracked into small, irregular polygons. Like dried mud or cracked paint. It is the lichen of the chalky patch. The one that looks like the rock is exhaling. What makes it special is the texture. Aspicilia crust lichen is one of the thickest crustose lichens in New Zealand. Its crust can be several millimetres thick. Forming a chalky, crumbly layer on the rock. The surface is rough and powdery. Like dried clay or plaster. When you touch it, it feels soft and slightly crumbly. As if it might turn to dust in your fingers. It is the lichen of the breath. The one that looks like the rock is exhaling. The one that makes the stone feel alive. The aspicilia crust lichen is a crustose lichen. This means it grows flat on the rock. Like a crust of paint. Rather than upright or leafy. Its body is a thick, cracked crust. Often forming circular patches or irregular stains. The surface is dotted with tiny, dark spots (pycnidia). These are the spore-producing structures. Under a hand lens, the spots are visible. Tiny dark dots scattered across the pale surface. Biologically, the aspicilia crust lichen is a partnership. A fungus and an alga living together. The fungus provides structure and protection. The alga provides food through photosynthesis. The aspicilia crust lichen is adapted to limestone and calcareous rocks. Which are rich in calcium. It can even grow on old mortar and concrete. To find aspicilia crust lichen is to find the chalky patch on the limestone. It is pale, crusty, and powdery. A living breath on the stone. You can run your finger over the surface. Feel the soft, crumbly texture. It is the lichen of the chalky patch. The one that looks like the rock is exhaling. The one that proves that even stone can be alive.