What is a bryophyte anyway?
By Shawn Krosnick and Kevin E. Indoe
The word bryophyte refers to a group of plants comprising the mosses, liverworts, and hornworts. There are about 25,000 different species of bryophytes in the world today. Although these plants are small in size, they are one of the largest groups of land plants and can be found almost everywhere in the world. There are more species of bryophytes than the number of conifer and fern species combined.
These plants do not flower and therefore, never produce seeds. A plant that does not flower is called a cryptogam and reproduces by spore production. The process by which they produce spores is termed alternation of generations.
Bryophytes do not have a true vascular system and are unable to pull water and nutrients up from the ground at any significant distance. Lacking this specialized system distinguishes bryophytes from ferns and flowering plants. It is for this reason that they are considered to be rather primitive plants.
Bryophytes are regarded as transitional between aquatic plants like algae and higher land plants like trees. They are extremely dependent upon water for their survival and reproduction and are therefore typically found in moist areas like creeks and forests. Some bryophytes, however, are able to survive in areas with little or no rainfall.
Liverworts and mosses have been found in the fossil record dating as far back as the Palaeozoic Era. Their true lineage still remains uncertain since the fossil record is rather poor. They are, however, believed to have shared a common ancestry with the green algae.
Bryophytes have very distinct characteristics that enable them to be separated into three distinct classes of the taxonomic hierarchy, the Hepaticae (liverworts), Anthocerotae (hornworts), and Musci (mosses).
Ecologically, bryophytes play a major role in maintaining an ecosystem's humidity level by their ability to absorb and retain water. Environmentally, they are often used as indicators of the habitat condition. Any change in water, soil and/or air quality, due to pollution or other factors, will have an impact on bryophyte growth. Commercially, Sphagnum is often used in soil mixtures to retain moisture. In the past, this moss was also sterilized and used as a packing for wounds.