Susie Huffman, age 10, of Charmco, West Virginia, for her question:
What exactly are spores?
If you kick a fat puffball at just the right time of year, it will puff out a dusty cloud of perhaps a trillion powdery spores. A few lucky spores will land on rich, moist soil and grow into giant fungi just like the parent puffball. The spores, however, are very different from true seeds.
Seeds, even tiny mustard seeds, are big enough to be seen. Spores are tiny specks usually too small to be seen without a magnifying lens. But both seeds and spores can carry on life to a new generation just like their parents. It is natural to think that spores are really seeds, perhaps just smaller than the usual seeds of the plant world. But this is not so. There are basic differences between them. Though spores are smaller, they come in more varieties and greater numbers. What's more, many spores can perform other duties besides handing on life.
A seed is a sleeping embryo, a life cell formed by the union of male and female cells. When the seed is surrounded by friendly conditions, it divides and multiplies into more cells. In this way the small miracle gradually grows into a copy of its parent or parents. A spore is no more than a speck of magic protoplasm with a nucleus. These are the basic ingredients in every living cell in the plant and animal kingdoms.
A tiny spore is much simpler than a seed. But it has a long history of success dating back to the earth's first single celled plants and animals. For millions of years, the plant world depended on spores to hand on life from generation to generation. What's more, many single celled plants and animals turned into spores to protect themselves. They encased themselves in tiny shells and rested through long spells of cold or drought.
Giant tree ferns spread their feathery fronds in the ancient coal forests of 300 million years ago. They developed ctops~af spores under their lacy leaves, just as modern ferns do. The ripe spores drifted off in dusty clouds and some of them became new tree ferns. In the soggy swamps, pale toadstools and other fungi produced spores for the next generations. In the ponds and puddles, countless one celled plants and animals spread swarms of spores into the water. Some of these miraculous midgets swam around by waving their hairy little whiskers. When the old swamps became dry, many bacteria and other tin living things grew shells. They rested safely inside, often for years, until the rains brought back enough moisture.
About 210 million years ago, the first simple seeds of the plant world were invented by the palms and pines. About 80 million years later, the first flowering plants began bearing their improved varieties of seeds. But the fern family and the swarming algae, and swarms of single celled plants and animals still went on producing their spores. And they still do. After all, their spores have proved successful for millions of years and there is no reason to replace them with new fangled seeds.
A parent plant or protozoan animal may produce its spores all by itself. Some spores, however, are formed from male and female cells, perhaps from two different parents. A bacterium may produce just one or a whole package of spores. Or the tough coated little plant may turn itself into a spore to avoid hardship. Some bacteria are dangerous to us, and this trick of protecting themselves often makes destroying them a difficult job.