Mosses and Liverworts
	What are they? Mosses and liverworts are usually small land plants. Their structure is quite simple. Unlike flowering plants and ferns, they do not have special channels to transfer nutrients up the stalk. Mosses and Liverworts grow well in clean unpolluted air. They also need lots of water. They do not have flowers, but reproduce by means of spores. If you look closely enough at these tiny plants, you will see that they are often very beautiful.
	If you use a magnifying glass or a microscope, you will be able to see the delicate detail of these plants in their full glory.
	There are hundreds of different types of mosses and liverworts. They grow like a green blanket, covering rocks, stone walls, roofs and bare spaces. Looking at mosses and liverworts, you would never know that they reproduce with lots of energy and activity.   Where do they Live? Mosses and Liverworts grow well in the countryside and where the air is clean. They can also be found surviving in towns and cities.They can be found growing on rocks, trees and stones, or will grow to fill bare spaces on soil. Lots of mosses and liverworts grow in the western half of Britain, where there is more rainfall than in the rest of the country. Many grow in wet mountainous regions. Although they like moisture, very few mosses and liverworts grow completely under the water. You can now explore, in more detail: Mosses Introduction Reproduction Examples Liverworts Introduction Reproduction Examples   Mosses - Introduction Mosses belong to a group called Musci. Looking at moss, it is hard to believe that they have a stem and leaves - but they do. The little leaves spiral around the stem, and usually have a central rib. Little structures, similar to roots, attach the plant to its base. Most types of moss are small, but the Common Bank Hair Moss (the largest British moss) may reach a foot or more in height. Unlike flowering plants, mosses do not have pores (stomata) for gas exchange. Instead, gases such as oxygen and carbon dioxide pass through the surface of the thin leaves.   Moss Reproduction Moss can reproduce by sexual and also by vegetative reproduction. Sexual Reproduction Male and female organs grow from mosses, and can be found in whorls of specialised leaves. Male organs produce male cells, which are able to swim to the female organs. This results in fertilisation (the fusion of male and female cells) and the development of the spore-bearing organs, which are capsules on stalks.
	Their job is to produce and disperse spores. The spores are held in place by little teeth-like objects. When it's the right time to release the spores, the little teeth open, and allow the spores to be ejected, in what looks like a fine dust.
	If you breathe on moss while looking at it through a microscope, you can watch the little teeth respond by opening up. A moss spore is miniscule. It is so tiny that air currents can easily carry it over huge distances. If the spore lands in a moist place, such as the bank of a river, or the moist floor of a wood, it will develop into a fine green thread of cells. Often, many spores travel and germinate together, so you might find a tangle of green threads - each thread having grown from a different spore. The threads eventually develop buds and leaves - which all grow over each other. This is why moss is so soft and spongy and matted together like a carpet. Vegetative Reproduction Some moss species hardly ever produce spore capsules. So how do they reproduce? New moss plants can grow directly from a bit of broken off moss leaf. The broken piece can grow into a new leafy moss plant. This is a type of vegetative reproduction.   Examples of Mosses Dicranoweisia cirrata This moss is common in Britain, and can be found on trees, logs, walls and thatching. These little plants grow to 2 cm in height, and have long narrow leaves. When the leaves dry out, they curl. The spores are produced inside a narrow capsule, which grows on the end of a yellow stalk. Unlike the Liverworts, the mosses do not need constant moisture. Fisidens Adianthoides This moss is found growing in different types of wet habitat, including boggy ground, riverbanks, and rock ledges. It loves mountainous regions. It has tongue-shaped leaves, which are golden-green colour. Its stems grow to about 5 cm high. Sphagnum Sphagnum is an unusual moss. It is quite tall, and has a central stem and little branches. The leaves are unusual, as they show a pattern of alternating green and clear cells. This moss forms very spongy cushions, full of water, often found in bogs and other wet places. Palustra sphagnum moss is a pale green colour, often with tints of darker green, and sometimes, pale pink. The wall of the spore capsules gradually dry up and shrink. Eventually, when the capsule has shrunk a lot - the lid is blown off and the spores released in a small explosion.
	Liverworts - Introduction Unlike mosses, the body of this plant does not have stems and leaves, but is made of flattened soft green lobes. Liverworts belong to a group known as "Hepaticae". They are called Liverworts, because people think they look like the different lobes of the human liver. In the case of the so-called "leafy-Liverworts" the leaf is divided into segments. Like moss, the Liverwort plant is attached to its base by root-like structures.   Liverwort Reproduction Liverworts can reproduce by sexual and also by vegetative reproduction. Sexual Reproduction Let us look at how the Wide-Nerved Liverwort reproduces. The male organs appear as little raised areas, and male cells grow inside them. The female organs are tiny flask-shaped bodies each containing an egg cell. A protective hood grows over the female organ, in order to retain moisture. In order for sexual reproduction to occur, Liverworts must be covered in a layer of moisture. The male cells grow little structures, which they use to swim through the layer of water, towards the female cells. The male cells are attracted to the female cells by chemicals. They swim through the neck of the female egg flasks, and fuse with the egg cell. Then, the fertilised cell multiplies to form a spore-producing organ. The spore capsule that develops is very pretty. When the capsule is ripe, it splits open and the spores are distributed. New plants grow from these tiny spores. Vegetative Reproduction If any piece of a Liverwort is broken away, it is able to grow into a whole new Liverwort plant. In some types, little buds, which grow inside special cup-shaped structures, or just grow from the tip of the plant. When the buds fall off, they develop into new plants, exact copies of the parent.   Examples of Liverworts Marchantia polymorpha Like all liverworts, Marchantia loves the damp. It is often found in the soil of flower pots, outdoors or in greenhouses. It can also be found by rivers and in other wet habitats. It can be easily identified by its little cup-shaped "gemma-cups", in which vegetative budding occurs.   Riccardia pinguis This is a very wet Liverwort. It can be found in marshy areas and on wet rocks. It grows to about 3cm long. The spore capsules are oval and dark green, and grow on long stalks. The capsule breaks open into a cross shape when it's ripe. The male structures grow on separate plants, and can be found tucked away inside the tips of the branches.