Mosses are small plants that typically form dense green clumps or mats, often in damp or shady locations.
There are at least 12,000 species of mosses.
These small plants are found all over the world. Their habitats ranging from the humid tropics to the polar regions, fallen logs to lakes, rivers, and streams. In fact, moss has been found just about everywhere, except in salt water environments.
Mosses are best known for those species that carpet woodland and forest floors.
In the arctic tundra, mosses can constitute 50 to 90% of the ecosystem’s biomass.
The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients.
Mosses are typically from 0.2 to 10 cm (0.1 to 3.9 in) tall, though some species are much larger.
Dawsonia, the tallest moss in the world [Photo below], can grow to 50 cm (20 in) in height. It is found in New Zealand, Australia and New Guinea.
Mosses do not have cells that move water like other plants – water must soak into them, like a sponge.
A patch of moss is made of many tiny moss plants packed together so that they can hold water for as long as possible.
Mosses do not have flowers or seeds, and their simple leaves cover the thin wiry stems. At certain times mosses produce spore capsules that may appear as beak-like capsules borne aloft on thin stalks.
Mosses are one of the most primitive types of plants, and their simple structures have remained largely unchanged over the course of millions of years.
They are more complex than algae yet simpler than the higher vascular plants.
Moss can benefit forests by forming a carpet that will slow down and retain water, therefore reducing soil erosion and helping to prevent water loss during dry periods; these moist, nutrient rich patches of plants also stop tree seeds from getting washed away and provide perfect conditions for germination.
While moss in some contexts is considered as a weed, such as growing in grass lawns, it also is popular for a number of aesthetic purposes, such as in Japanese gardens, in old temple gardens, and for some home decoration and floral display purposes. Moss is thought to add a sense of calm, age, and stillness to a garden scene. It can also make brick wall very interesting like on the photo below.
Moss is also used in bonsai to cover the soil and enhance the impression of age.
Dried moss can be rehydrated and will return to life. Dried moss is a dormant plant that with tender loving care can begin growing again.
Moss is harmless. It does not produce any dangerous spores or fumes, it contains no poisons or irritants.
In World War I, Sphagnum mosses were used as first-aid dressings on soldiers’ wounds, as these mosses said to absorb liquids three times faster than cotton, retain liquids better, better distribute liquids uniformly throughout themselves, and are cooler, softer, and be less irritating.
Many small plants bearing the name moss are in fact not mosses. The “moss” found on the north side of trees is often the green alga Pleurococcus. Irish moss is a red alga. Beard moss, Iceland moss, oak moss, and reindeer moss are lichens. Spanish moss is an air plant of the pineapple family. Club mosses are fern allies in the family Lycopodiaceae.
Mosses play an important part in the lives of many small animals. Certain mites and spiders live in mosses. Some birds use moss fibers to build or line their nests. A creature in New Guinea named Weevils have been found with mosses growing on their backs. Mosses serve as camouflage for insects.
Most botanists believe that mosses evolved from aquatic ancestors but there is debate about their evolutionary ancestry.