While walking along many of our forest trails, carefully avoiding stumps and rocks that could lead to awkward trips or painful falls, we might see a carpet of dark green mosses on the forest floor and faintly green curious scaly growths on rocks and lower portions of tree trunks.  The latter growths are not plants, nor animals, but are lichens: a curious partnership between a fungus and a photosynthetic organism.  The fungus partner is more like a mold than a mushroom but like all true Fungi lives on absorbing dissolved decaying organic matter.  The fungus consists of branched filaments (hyphae) that form a tangled mass.  In lichens, unicellular green algal cells or cyano- bacteria…formerly known as blue-green algae…are interspersed within the tangle of fungal filaments.  Although the photosynthetic cells may be found as free-living organisms the fungal partner in lichens is not.  The photosynthetic algae produce food (carbohydrates) for themselves as well as their saprophytic fungal friends.  What do the algae gain from this symbiotic relationship?  Some suggest that the fungus protects the algal cells from drying out.  Maybe so.