CRUSTOSE LICHENS

Crustose Lichens can only be removed by cutting the bark on which they grow. Stem and leaves of these crust-like thalli cannot be differentiated. They lack true roots and a vascular system...

Opegrapha ochrocheila The thallus is very thin, light grey and sometimes tinted green or brown. It may be immersed in the substrate. The black apothecia measure 2.5mm or smaller. Examined with microscope.

Lecanora barkmaniana A lichen possibly under-recorded that is spreading rapidly onnutrient-enriched or dusty trees. Lecanora barmaniana has a light grey thallus with a lighter grey prothallus.Dotted soralia with light yellow-green soredia spread over most of the thallus. The rare light brown disc apothecia have crenulate edges. Pycnidia, flask-shaped fruiting bodies bearing conidiophores and conidia on the interior, are absent.

Lecidella elaeochroma Often found on the bark of young ash trees. The vegetative body of the lichen known as the thallus is greyish-white to light greyish-green. The spore-bearing discoids (apothecia) are small and black. Very common.

Lecanora chlarotera The spore-bearing discoids (apothecia) have thick edges and range in colour from buff to chestnut brown. Very common.

Lecanora muralis Waxy-looking greenish-grey to yellow-grey crustose lichen that grows on rocks, concrete walls and pavements. It may be tightly or loosely attached to the substrate, normally growing in rosettes radiating from a centre filled with disc-like fruiting bodies (apothecia). Occasionally found on bark.

Graphis scripta  The smooth or wrinkled thallus of Graphis scripta is white or grey. The apothecia can be curved or arranged in a radiating pattern like that of a star, with raised unfurrowed edges. Found on smooth-barked trees.

Candelariella aurella A mustard-yellow crustose lichen known as the Hidden Gold-speck lichen, or Egg-yolk lichen. It is common on nutrient-enriched calcareous rocks, bricks, mortar and wood that are exposed to sunlight. This was growing on a wooden gate.

Arthonia spadicea  A lichen of shaded bark. Arthonia comes from the Greek language meaning 'to sprinkle'. This species has the appearance of sprinkled tar spots. The apothecia grow to about 1.5mm long.

>>> Next: Foliose Lichens