Lichens are unique combinations of a mycobiont (the fungus partner) and a phycobiont (the algal partner). Often, in spite of hot dry weather conditions, they are the most abundant fungal organisms found in the environment. Lichens occur on a variety of substrates, including dead branches, bark of trees, moss and even various types of rocks. Species of Lichens are normally habitat specific. However there are some that can occur on a number of substrates.
There are four major growth forms of lichens; foliose, the thallus consists of large leaf-like-lobes; crustose, the thallus is flattened, lobes are small and adpressed to the surface of the substrate, crustose lichens have a lower cortex and are anchored to the substrate by rhizines small rhiziods; squamulose an intermediate form between foliose and crustose, the thallus consists of numerous small lobes or squamules; and fruticose, the thallus is shrubby.
Teloschistes chyrsophthalmus, center, on a fallen oak branch flanked by two colonies of Physicia aipolia. Note the small round yellow apothecia.
Close-up of Teloschistes chrysophthalmus showing cilia surrounding the apothecia.
Xanthoria candelaria. A yellow-orange fruticose, bushy lichen with no apothecia, often found with Teloschistes on dead branches.
Physcia aipolia with a light gray thallus and black apothecia, arrow, on oak bark.
Parmelia bolliana gray foliose lichen with large brown apothecia (dried condition).
Cladonia chloropheae on sandstone illustrating how lichens can inhabit spaces within rocks and show only fungus fruiting bodies, apothecium, (8 to10mm high X 4 to 5mm wide), and small squamules scattered around the rock.
Lecidea tassellata, a crustose "tile" lichen on sandstone.
Unidentified green-crustose lichen on granite at 10 acre rock, Ravia, OK.
