There Are Variations In Growth Types In A Single Lichen Species, Grey Areas Between The Growth Type Descriptions Stock Image

There are variations in growth types in a single lichen species, grey areas between the growth type descriptions, and overlapping between growth types, so some authors might describe lichens using different growth type descriptions. When a crustose lichen gets old, the center may start to crack up like old-dried paint, old-broken asphalt paving, or like the polygonal `islands` of cracked-up mud in a dried lakebed. This is called being rimose or areolate, and the `island` pieces separated by the cracks are called areolas.