Crustose lichens
Crustose Lichens are the simplest form of lichen which is a crust on the surface and are highly variable in anatomy... This crust is closely attached on the surface of the substrate on which they are growing. This crust can be quite thick and granular or actually embedded within the substrate are hard to remove without damaging the substrate or the lichen itself. These lichens tend to grow out from their edges and have their fruiting bodies tiny cups in their centre. (the lichen's spore-producing reproductive structures). Their growth tends to radiate, in that the mitotic regions are at the margins, and the centre is more likely to be dying.
Their edges are flat, unlobed with indistinct edges that don't turn up at all. This is one way to distinguish crustose from foliose lichens. It is sometimes to tell the Crustose and Foliose apart because young colonies of foliose lichen can have poorly developed edges and look very much as if they were crustose.
They can be found covering rocks, soil, bark, etc. -- often forming brilliantly coloured streaks.
Crustose lichen, Baeomyces spp. The fungal partner of most lichens reproduces by shedding spores from its splash cups. These pink splash cups are on the upper surface. In wet conditions, the cup releases its spores and some are carried away on drops of water that splash into it. Once a fungal spore germinates, it needs to combine with a photosynthetic partner before it can form a new lichen.
A brown crustose lichen on a dead log. (Lignicolour lichen) meaning its growing on non-living wood [lignum)
Crustose lichen on a boulder
A crustose lichen on a rock estimated 20 years old with its centre dying
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