Lichens are a symbiotic association between algae and fungus. The algae is a layer of single-celled plants on the surface, just below a gelatinized layer of fungal hyphae. The algae captures nutrients that land on it's surface and provide energy through photosynthesis, while the fungus absorbs moisture, and provides a protective structure for the algae. These are otherwise independent organisms, capable of surviving without each other. Lichens can insert threads a half inch into solid rock. These threads are not true roots, but anchors. The fungus produces a potent acid, which is combined with an alcohol from the algae to form acid crystals. The varied and often bright colors of the lichens come from these acid crystals. The acid is used to etch holes in the rock, and threads are inserted for anchors (Platt). Most of the so-called "mosses", especially those found in trees, are actually lichens. The true mosses are distinctively green like other true plants.

Lichens gather most of their nutrients through their surfaces, directly from the air and rain. This habit gives the lichens an adaptability to live almost anywhere, even on rocks, trees, or buildings. ... The Lichen Division is comprised of at least 8 orders, 45 families, and 6,000 species. Information on the edible and medicinal uses of the lichens is scattered. Many lichens are known to have potent antibiotic properties, and many are edible. However, some lichens do contain toxic substances, so you should not graze randomly on them.

Gyrophora -Rock Tripe
The lichen is edible, especially when boiled with meat (Sturtevant).
Umbiliceria-Rock Tripe
This lichen is edible cooked. Soaking in a couple changes of cold water will help to remove the bitterness. They are said to be mucilaginous, great for thickening stews (Angier). It also has antibiotic properties (Angier).
Lecanora-Cup Moss, Manna
The plants are edible (Sturtevant). One species, growing in the middle-east is the "manna lichen". During drought years the plant may be broken apart by the wind and blown across the land. This lichen became immortalized in the Bible when it showered down on the starving Israelis as the "manna rain".
Cetraria-Reindeer Moss
Reindeer moss is bitter, antibiotic, and edible. The lichen is used as an expectorant to stimulate the release of phlegm, apparently due to the bitterness. This bitterness needs to be removed to make the plant edible. The lichen should be soaked over-night and for most of a day, in two changes of cold water to remove the acids, then strained and eaten (Angier). It is a source of gelatin (Asch).
Alectoria-Black Tree Lichen
The black tree lichen is stringy and "moss" like. Montana Indians washed and soaked the lichen, then cooked it for one to two days in a steam pit. The cooked lichen was eaten or dried and powdered and used as a mush or thickener later. It is reported thatFlathead Indian families ate 25 pounds of the lichen each year (Hart).
The plant is edible (Sturtevant). A thick tea is used on running sores (Murphey).
Letharia-Wolf Lichen
This bright yellow tree lichen contains a highly toxic acid. It was once combined with animal fat and nails and used in Europe to kill wolves (Vitt). It is also used as a dye plant.
Usnea-Old Man's Beard
The lichen is boiled for use as a dye (Gilmore). It is used medicinally as an antibiotic (Klein). (Usnea is a light grey color. Use the "rubberband" test for positive identification: break the stems and inside you will find a white, rubbery core that stretches a little like a rubberband.)
The lichen is edible (Sturtevant).
Claydonia-Pixie Cup Lichen
The Cladonias contain didymic acid, used as an antibiotic against tuberculosis (Mabey). It is reported to be edible (Sturtevant).
Cladina-Reindeer Lichen
Some species were boiled and the tea was taken for colds or as a laxative.

Thomas J. Elpel
Hollowtop Outdoor Primitive School
Pony, Montana