|LICHENS grow in abundance in Tasmanian rainforests.
They are a combination of a fungus and an alga, coloured green, white, grey
or brown. The alga provides food for the fungus, which then envelops the alga,
providing shelter and nutrients. Although these are very abundant and diverse
in nature, those which form lichens rarely exist separately.
There are three broad groups of lichens. Crustose lichens form a crust and are closely attached to a rock or tree. These are responsible for some smooth tree trunks being white. Foliose lichens have a thin leaf-like appearance, often with branches. Fruticose lichens are the bushy-branched structures which, in their best development, hang in long streamers from rainforest branches
Stereocaulon is a cosmopolitan genus found on rocks and soil. Most Tasmanian species are exclusive to alpine areas but two very widespread species also occur in the lowlands and can be found in rainforest vegetation. It has a gall-like structure (cephalodia) containing blue-green algae which may be important in nitrogen cycling.
Stereocaulon ramulosum (pictured above) is characterised by a pale greyish, shrubby thallus (body of the lichen) with conspicuous red-brown apothecia (disc-like fruiting bodies) and bluish-grey warty cephalodia.