Richard Potteiger, age 9, of Pittsford, NT. for his question:

What are lichens?

Somebody has been finger painting on the side of a big lumpy rock. No, those pale blotches of pearly grey and rosy pink are lichens. Somebody has hidden a baby moss plant under the fallen leaves. No, that tangled wad of pale green threads is also a lichen. That poor old tree trunk is breaking out in colored blisters. No, those spreading rashes are also lichens.

The lichen is a small and shy member of the plant family. It never grows showy green leaves or eye catching flowers. We might hike through the woods all. day without noticing a single lichen. But we would pass thousands of them on tree trunks and fallen logs, on the ground under fallen leave, and hidden among the gentle mosses.

We know that there are 15,000 different lichens and there may be more, just waiting to be discovered. They come in many shapes and many colors. Some look like flat roses painted on rocky boulders. Others look like miniature sponges, wads of cotton or scraps of crinkled paper. Some of them are deep purple, deep blue or black. But most lichens are dainty blends of pale pastel tones of greens and greys, blues and yellows, creams and browns.

The shy little lichens do not look important. But actually they rate among tiie most important plants on the earth. They grow where no other plants can grow, high on the mountain slopes, under the wintery snow and even in frozen polar regions. When the sea leaves a new patch of land high and dry, the lichens are the first plants to grow there. And as they live and die they form rich soil for larger plants to feed upon.

Each lichen is actually a partnership between two different plants.

Ono partner is a fungus, a small cousin of the mushroom. The other is an alga, a land dwelling cousin of the sea weeds. The fungus is a spongy tangle of pale threads. Like the mushroom, it has no green chlorophyll and so it cannot make its own food from air and water as other plants do. But it can trap and hold pockets of dewy moisture among its spongy threads.

The alga has chlorophyll and it can make plant food from air and water. But it needs lots of water to survive on the dry land. And the fungus has many pockets full of water. The two little plants live in a give and take partnership. The fungus provides the extra water for the alga and the alga makes enough plant food for both partners.

This give and take is called symbiosis and each lichen hands on the family partnership to its children. When the time comes, tiny grains appear on the parent lichen. Each is a small wad made from a few cells of the alga wrapped in a few spongy threads of the fungus. The wind blows away the little granule and when it settles down it starts a new lichen.