• Mosses often grow in large dense mats.Ryan McVay/Lifesize/Getty Images
  
  Mosses are a member of the bryophyte taxonomic group, which also includes liverworts and hornworts. With over 20,000 species in the group, mosses are diverse in form and live in a wide range of habitats from arctic tundra to tropical rain forests to arid deserts and everywhere in between. Despite their diversity, however, all mosses have certain physical characteristics in common.
  
  

Rhizoids

• According to the Australian National Botanical Gardens, all mosses possess rhizoids, which are strong rootlike structures at the base of the plant. Rhizoids provide an anchor to hold the plant to the substrate it is growing on. Unlike true roots, however, rhizoids do not absorb water or nutrients from the soil. Depending upon the species, the rhizoids of mosses may be sparse or substantial and dense.
  
  

Stems

• Mosses possess stems that are generally weak and short. The erect stems of some species give a fuzzy or cushiony appearance, while others species lie flat and creep or sprawl along the ground. Stem colors can vary from shades of brown to bright green.
  
  

Leaves

• The stems are often covered with small green leaves. The leaves contain chlorophyll and carry on photosynthesis, which provides nourishment for the plant. In dry conditions, many mosses possess leaves that will fold up or curl to protect the plant. When exposed to moisture the leaves unfold, giving the wet moss a very different appearance compared to its dry state. Moss leaves are generally small and are attached directly to the stem.
  
  

Reproductive Organs

• Mosses possess both male and female reproductive organs, respectively called the antheridia and the archegonia. The antheridia produce the sperm for the plant and may be attached to the end of the main stem of the plant or on short side shoots from the stem. The archegonia produce the eggs which, when fertilized, becomes sporophytes.
  
  

Sporogonium

• In most mosses, sporophytes mature in a fruiting body called the sporogonium. This a capsule-shaped growth that usually forms at the end of a thread-like filament called a seta. The seta typically grows from the end of each moss stem. When sporophytes within the sporogonium eventually mature, the sporogonium opens, allowing the spores to disperse and germinate to produce more moss plants.