The phylum Bryophyte comprises all land plants (embryophytes) which are non-vascular. The non-vascular means that the plants of this type do not have the vascular tissue of other plants that is used to circulate liquids throughout the plant. These plants also reproduce using spores and do not have any seeds nor do they flower. There are three classifications or groups of bryophytes and these are bryophyta, anthocerotophyta, and marchantiophyta.
Bryophytas, more commonly referred to as mosses, are one of the three groups of bryophytes. The moss group comprises about 12,000 different species. These plants range from less than one inch in height to around four inches. Mosses prefer damp or shady locations and tend to grow in groupings or clumps. It is sometimes difficult to differentiate between mosses and the other two groups in the Bryophyte designation and the reverse is also true. At one point there was only the Bryophyta classification. Mosses can be distinguished from the other two groups because of the multi-cellular rhizoids and by differences in the leaves and stem structures of the plants.
Mosses lack a cuticle (waxy covering of the plant) they usually require moisture because they can lose water through the surface of the plant. They typically live in wooded areas or along streams but are found in places all over the world. Mosses can’t survive in dry, hot environments that are windy or cause the moss to be in direct sunlight.
Anthrocerotophytas also go by the name hornworts. These comprise only about 100 species but more are being discovered each day. The hornworts are named for their distinctive feature that separates them from the other classifications. This feature is the horn-like sporophyte structure that is present on most hornworts. The bodies of the hornworts are usually a thin structure typically around one inch or less in diameter and vary in length. The body may have branching structures or be ribbon-like.
Hornworts are present all over the world and prefer humid, shaded conditions like the mosses. They are typically found in the soil but some of the larger species that live in tropical areas grow in tree bark.
The final classification of bryophyte is the marchantiophyta which are more commonly called liverworts. The naming is due to the unproven historical belief that these plants could help with liver problems. The liverworts have individual stems that are less than an inch wide and usually less than 4 inches long. Like the hornworts they have a branching structure or ribbon-like plant body. There are likely upwards of 10,000 different species of liverworts in the world.
Unlike the other bryophytes, the liverworts have oil containing bodies in some of their plant cells which separates them from the mosses and hornworts. Hornworts can grow on just about any surface and are found in habitats all over the world. They usually require moist shaded areas which does not leave them in direct sunlight. Typically they are not found in dry desert climates but there are types of liverwort that can stand the desert and direct sunlight.