A Visitor Learns about Lichens
By Gordon P. Walker, Ranger-Naturalist
“Ranger, is that sulphur on those rocks over there?”
“No, sir, the bright yellow color which you see is a lichen.”
“A lichen? What in the world is that?”
“A lichen is a form of plant life which results from a combination of a fungus and an alga. Any one of a number of fungi may combine with a single alga or any one of these fungi may combine with several different algae. Each one of these combinations results in a separate species of lichen having a distinct color and form. Both of these factors are a result of the interaction of the two members of this relationship and rarely, if ever, do they resemble either the alga or the fungus as it grows alone. The color seems to be connected with special chemical compounds, each produced only by a single pair.”
“Does just any old fungus and alga, as you call it, get together in this way?”
“So far only one group of fungi have been found in lichen associations of the temperate region. These are the cup fungi or Ascomycetes. In the tropics, fungi closely related to the toadstools also combine in this way. Three kinds of algae are found in lichens; brown, blue-green, and more commonly green algae. Ordinarily only the single-celled algae combine, but occasionally a filamentous form has succeeded in doing so. Scientists have been able to break them down into their two components and grow them separately in the laboratory, they have never been able to recombine the two under artificial conditions.”
“Why should the two combine anyway? Wouldn’t’ they compete with each other?”
“On the contrary, in nature they help each other out. You see, the fungus is an excellent water absorber and it also can get a grip almost anywhere, but it lacks the ability to make its own organic food. The alga, having green color just like the grass or trees, can use the energy from the sun in the manufacture of sugar. Some of this sugar goes to the fungus which in turn gives the alga a good environment in which to live. In this way the two of them together are able to live in very difficult places such as the surface of bare rock, where neither of them could singly. In fact they are the first form of life to invade any new rock formation and to the all important first work in the breaking down of rock to soil.”
“Hmm, right out on bare rock, eh? Do they grow anywhere else?”
“Yes, the forms which grown on trees, you would call mosses. The yellow moss on the trunk of that hemlock there is one called the stag horn lichen. Although it grows on the trees, it is in no sense a parasite. It may get some mineral material from the dead outside bark to which it is attached, but it does not penetrate into the living tissue of the old tree and derives no organic foodstuff from the tree. It grows equally well on living and dead trees or branches. You will notice that it doesn’t grow down to the ground in very many places. This is because it doesn’t do well when it is buried underneath lasting winter snows. Thus the bottom of the lichen growth indicates the level of the normal persistent snow. At lower elevations there is another lichen, the goat’s beard, which grows in the same manner on the same trees. It looks somewhat the same but the color is lighter and it usually is somewhat longer. At around 5,200 feet there is a sharp line where the goat’s beard suddenly gives way to the stag horn which we see up here.”
“The black moss which hangs so thickly on the lower limbs of the alpine fir there to your right is known as the squaw’s hair lichen. I have been told that it was used as a famine food by the Indians. Deer eat it in wintertime, but in summer it is a hazard, since it burns readily and a tree will literally explode if humidity is low and a match or other flame is touched to it. Another edible form, called rock tripe, grows on the rocks up the trail. Other forms grow on down logs and some flat on the ground.”
“Golly are there many of these things?”
“Yes, although many of them have not been identified as yet, there are probably from seventy to a hundred of them in the park and the known forms throughout the world number in the thousands. Some of them are exquisitely delicate and others are brilliantly colored, such as the one which splashes the northeast side of the Phantom Ship with gaudy orange. If you are interested in them, go up the Garfield trail where you will see the rocks covered with veritable gardens of them. They are particularly showy right after a rain. The moisture seems to bring out their colors as they blossom out into renewed growth.”
(Much of the information contained in this article was obtained by private communication from Dr. F. P. Sipe, Associate Professor of Botany, University of Oregon.)
The purpose of a National Park is to protect and preserve in a primitive, a natural state, the most significant examples of floral and faunal types; as well as of scenery, so that scientist, nature lover, and the general public may see, enjoy, learn and benefit.
