Moss, A Plant

Moss is made up of many little green plants. Mosses affect the communities in which they live as they supply food and shelter for small animals and insects.

Mosses are small green plants growing in dense clusters in damp, shady places. Mosses can look like a green carpet. It will grow on fallen logs and at the base of trees or in shady areas. You might want to take a few minutes and examine these little green plants. Most mosses grow on land but a few live in fresh water. Carefully pick single plants from the moss "carpet" and examine them under a good hand lens or a binocular microscope. These are an excellent example of primitive land plant development.

A container for land plants is a terrarium. You can also grow moss in an empty aquarium. You will need to place some oil in the bottom of either the terrarium or the empty aquarium, then place the moss "carpets" on top. Next you need to fill the surface of the moss with water, keep the moss layer damp but not flooded with water. A piece of glass placed on top of the aquarium keeps moisture in the plant dwelling.

These nonvascular plants have an ancient lineage. Moss plants are the most common of bryophytes and have about 24,000 species. The bryophytes are structurally the simplest of all land plants. A moss plant body has no roots and has tiny cellular threads that serve as anchors. The structures look like a stem, root or a leaf although the "leaves" of the moss are only thin sheets of cells, usually a single layer. The leaf like structures will curl up and dry out when water is unavailable and then revives when they obtain water. Mosses are not as developed as some higher land plants are; their water-absorbing cells cannot reach more than 2 centimeters into the ground. When enough moisture is not available, the top layer of soil dries out and the mosses either die or stop growing until it rains. The thin and delicate structure of the "leaves" causes them to lose water very easily. Water is unable to rise rapidly through the stalk to keep the plant alive. Most of the mosses have long parenchyma cells into which water moves by slow, cell-to-cell diffusion.

There are single rows of cells growing out into the soil with no part of the plant having any vascular tissue. The water passes from cell to cell up through the stalk to the "leaves," which carries on photosynthesis. Moss will make their own food through photosynthesis. Photosynthesis sunlight energy is trapped by pigment molecules (such as chlorophyll), and is used in the formation of intermediate energy carriers (ATP and NADPH2). These carriers transfer some of their energy to reactions in which carbon dioxide and water from the environment convert into food molecules.

Spores of moss germinate forming a green, threadlike filament that resembles filamentous green algae. This gametophyte filament produces the moss plant. A haploid moss plant can have both male and female reproductive structures, or both. Sperms and egg cells form at the top of the moss plants. The sperm swims through the dew to reach the egg cell, and then the fertilized egg cell develops into the bristle and spore case of an adult plant. When sperm and egg do fuse, the resulting zygote divides mitotically, which produces a diploid saprophyte. The saprophyte on a stalk growing out of the tip of the gametophyte body is dependent upon the haploid plant. A thin bristle develops on the top of the moss plant at times, above the green part with a spore case at its end. The spore's fall out of this case as salt falls from a saltshaker. The wind carries the spores that may land on moist soil to form new moss plants.

Peat moss is a large type of moss as it grows thick and often becomes a dominant plant in an area. It contains many hollow spaces that will soak up and store water and are very absorbent. When the moss grows upward, the lower parts die and pack down into bog water. The moss becomes a peat deposit, as it does not decay fast as the water is acid. Thus, peat is a simple mass of partly rotted plant remains. Gardeners need to have their soil loose and more absorbent so they buy bags of peat moss and use it to pack around the roots of plants. Tender plants ship easily with peat moss surrounding them as the moss holds water and keeps the roots moist.

The liverwort is a relative of the mosses and found in damp, low woodlands, and even along banks of streams. You might find some floating in water but these are not as common as mosses and are so small you could walk on the ground and never notice them. The bodies are flat, ribbon-shaped structures. On the underside of the liverwort are a large number of root like cells growing into the soil to absorb water. These plants have no true roots, stems, or leaves. They do not adapt well to land.

Mosses affect the communities in which they live as they supply food and shelter for small animals and insects. They protect soil and keep slopes from washing away during rainstorms or severe weather. They also aid in forming new soil. Acid produced by the root like parts of the moss slowly soften the rock when they grow in shade over rocks. This acid breaks down into the soil and the dead moss parts will turn into humus then larger plants will have sufficient soil to grow.

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