Kathy Painter, age 10, of Wichita, Kansas, for her question:
How does moss form?
Mosses grow where the air is damp and the sunshine filters through friendly shadows. At a glance, they look like velvety rugs and carpets in assorted shades of green. They are lovely to look at and spongy soft to the touch. But under a microscope or even a magnifying glass, each little rug becomes a miniature vision.
Each mossy tuft is a tiny tree, decked from top to bottom with ruffles and collars of green foliage. Massed together, the little trees become a lush fairy forest. The dense, spongy foliage can trap and hold the dew from one day to the next. The mossy plant is anchored to the ground by fine threads called rhizoid.§ which soak up water and minerals from the damp ground.
There are no flowers and no seeds in the mossy fairy forest, though sometimes you may be fooled. Certain leafy mosses are crowned with rosettes that look like green flowers and the vivid green pincushion moss at times wears yellow pins that look like seeds. Mosses„ like all living things, hand on life to their children. But only the more advanced plants have flowers and seeds. Mosses were among the first plants to inhabit the dry land and since those far off times they have been handing on life through spores . tiny seedlets which can be blown into a cloud of fine dust.
At the right time, certain of the tufts send up fine threads which carry egg cells. Other mossy tufts send up threads which carry sperm cells. The cells ripen and wait for the first dewy morning, Then the sperm cells break loose and swim off in the fine film of moisture which covers the leafy moss.
Most of the little sperm cells get lost at sea. But one is sure to reach and join an egg cell. This new cell begins to sprout. It takes root in the tuft of moss which produced the egg cell and then sends up a fine green shoot. The top of the shoot is swollen, for it is a spore capsule. Inside there is a host of tiny spores. The center of the flowerlike leafy moss is a spore capsule and so are the pins on the pincushion moss.
The capsule is a crisp little shell with a lid. At the right moment, the lid pops off and the ripened spores scatter away on the breezes. They become part of the dust and debris in the everyday air, most of which is too fine for our eyes to see.
The voyaging moss spores are wafted high and far. They have been found drifting miles above the wide oceans, Some fall into the sea and some fall on the desert where there is not enough shade and moisture for a moss plant to grow.
The little spore which lands on a warm, moist shady spot is off to a good start. It soon becomes a fine green trailing thread. The underside of the thread puts down rhizoids and the upper side sprouts green mossy tufts.