Moss and liverworts are such simple plants that they do not flower nor do they produce seed. Liverworts tend to be on the smaller side, growing from 1/16 of an inch to a foot, however, it is unusual for them to get over six inches in length. These plants produce their food through photosynthesis, which can explain their small stature.
Story tells that liverworts received their name because they resemble the lobes of human liver. Liverworts display a flat frond, or thallus; whereas moss wall have a definite stem and leaves (and have a midrib). Neither of these plants have true roots, but instead, have rhizoids; or root-like filaments. These rhizoids act like roots to ground the plant and to withdraw materials from the ground to aid in making their food. Because of the photosynthesis, these plants have green color, however how small, due to the chlorophyll.
Moss and liverworts may not be respected plants, but they do provide assistance in conserving and producing soil. As moss and liverworts grow, their rhizoids invade the ground or rocks in which they are growing on. This helps water get into the soil, and into the rocks. Sometimes when the moss grows on rocks, it breaks away tiny pieces of rock and then mixes with other organic material to form new soil.
Both plants have a sexual generation followed by an asexual one. These alternate for reproduction. In the asexual generation, moss produces airborne spores, which are one celled organisms with a protective wall. These spores flow about in the atmosphere and when they come to rest in a damp favorable surface, they will continue to grow. This process is called germination. During the growth of the new moss, it may resemble algae; then buds will develop into leaf-like shoots. The rhizoids then take root and will grow.
In the sexual generation, some of the tips on the moss will become fertile and will produce sex organs. Egg and sperm cells grow and fuse into one cell called a zygote, followed by a embryo, and the asexual generation. There is also another way that moss reproduces. Often times in climates that are too dry, spores will not be formed. In this case, pieces of branches may break off and get carried away with the wind. If these pieces land in a favorable climate they may grow. This is called vegetative reproduction.