Lichens

Part I of Essay
LICHEN. On places like tree trunks, rocks, old boards, and also on the ground grow strange splotches of various-colored plant life called . They are of great scientific interest because they are not single plants; instead, each lichen is formed of a fungus and an alga livin ....

Part II of Essay
.... they grow almost entirely underground and obtain light and moisture through small openings in the ground. Few grow near cities because most cannot survive in industrial air pollution. There are notable exceptions, however: in England, for example, Lecanora conizaeoides is actually confined to areas of high pollution. The body of the lichen, the thallus, has three basic growth forms. These forms are crustose, foliose, and fruticose. Each form is adapted to live under different moisture conditions. The crustose resemble a crust that has becom ....