Truffles are subterranean fungi with solid, globular fruiting bodies. They grow mainly in broad leaved woods. The perigord truffle of southern France is a much prized and very expensive delicacy. The traditional way of finding truffles is to train pigs or dogs to sniff them out. Most attempts at cultivating truffles commercially have failed.
Gills and Pores
The typical mushroom gets its food from decaying matter in the ground. Its fruiting body is spherical when it first bursts through the soil, but it quickly expands to form a cap and stalk. The latter, often called the stipe, may have a ring showing where the rim of the cap was originally attached and there may be a cup or volva, at the base. Under the cap, most species bear numerous fragile gills arranged like spokes in a wheel. The gill surfaces release millions of spores, the equivalent of seeds in flowering plants. Other mushrooms looks more like sponges, scattering their seeds from thousands of minute pores.
Lichens are among the hardiest of all organisms, growing in some of the hottest and coldest places. They clothe much of the arctic tundra. Each of the many species is actually a combination of a fungus and an alga. The alga can exist along, but the fungus cannot, so lichens are regarded as special kinds of fungi that rely on algae to provide much of their food.