Lichens and Sedums on Rocks
A ‘garden’ landscaped growth affinity on coastal rocks of lichen, alongside a complimentary background of sea sedum which keeps to a low height absorbing moisture in thick fleshy leaves, establishing itself on grassy ground and moist rocky crevices.
Lichen Orange: Caloplace thallincola Lichen White: Crustose lichen. Lecanora rupicola (british lichens.) good photo on lastdragon.org (Rimose type; thallus is initially continuous but becomes cracked into irregularly-shaped and sized pieces) or Sea Ivory – Ramalina Cuspidata (west coast) or Diploschistes caesioplumbeus. Lichen Pale Green: Sea Ivy – (family Ramalinaceae) : Ramalina siliquosa similar to lichen found in Exmoor rain forests. Lichen Black: Tar Lichen, shiny surface Verrucaria maura : ‘forms a thin, matt-black layer on rock surfaces that can resemble an oil stain. Reproductive bodies may be present as tiny black spots. Under magnification the surface is seen to be covered with a mesh of fine cracks that resemble dried mud’. (or Plcynthium nigrum, rougher surface)
Lichens are ‘dual’ organisms. They consist of two (or more) different life-forms living together symbiotically in a more-or-less well defined body or thallus. info The main partner is the fungus or mycobiont. The other partner is a green alga or a cyanobacterium (the photobiont). Many cyanobacteria are able to fix nitrogen which is an essential nutrient. In 10% of lichens (e.g. Collema and Leptogium) the photobiont is a cyanobacterium. The nutritional benefits of having a nitrogen fixing capability is why some lichens, where the primary photobiont is a green alga, have evolved separate structures called cephalodia which contain cyanobacteria (the secondary photobiont). So for these lichens there are three partners in the symbiosis.
Lichens are named after the fungal partner.