Lichen species present on only certain bricks

Lichen species present on only certain bricks

Observation - Lichen species present on only certain bricks. Description: There are a range of lichen species present, but primarily on two bricks in this photo. There are some yellow and green crustose species on the darker bricks, but on the rougher bricks which seem a different type are different species. There are white, b

There are a range of lichen species present, but primarily on two bricks in this photo. There are some yellow and green crustose species on the darker bricks, but on the rougher bricks which seem a different type are different species.
There are white, brown and orange/yellow crustose species and these are more abundant than those on the other bricks.