mildew, and the green algae of seaweeds. They are shipwrecked sailors, who learned a new way of life through many hardships.
Like the fungi, lichens live on other plants. They cannot get their own living. But, like the algae, they have learned to cling, to spread into leaf-like fronds, and to form spores or bud cells. In them is a hint of coming roots and leaves and seeds. They are often beautiful and are always curious. They are generally flat, dry, crinkly-edged scales, colored gray or silver or black. Sometimes, on old tree trunks, they are in thick, fluted ridges, and colored yellow or bright orange or white. With a microscope you can see that the gray scales are powdered with dusty round dots. Those are the spores or bud cells. When ripe the wind blows them, or the rain washes them away.
There is another thing the lichen has learned. Unable to turn green and so make its own food, it often goes into partnership with its higher born water cousin, the algae. It does it in this way. The lichen is made up of a network of thread-like cells. Each mash holds a little water. Algae spores, floating in the air and looking for water to grow in, find enough for just one cell, perhaps, in each mesh of the lichen. So they promptly move in. Often there are so many algae plants on the gray net surface of a lichen, that they turn it to a soft sage green color, very bright and moist. The algae being green, collect food from the sun and air and feed the lichen, and the lichen covers the algae with a network of gray thread cells to keep it from getting too dry.
Nature makes many partnerships between plants and animals that can help each other. Bees and butterflies help the flowers grow seeds. Men help plants to grow, and make friends of horses and dogs. Isn't it wonderful that, as low in the scale of life as algae and lichens, we should find this water plant and its shipwrecked cousin helping each other? (See Algae, Lichen, Chlorophyceae, Chlorophyll.)
