What are they? Mosses(Division: Bryophytes) are small plants that lack woody or vascular tissue. They require an environment temporarily saturated with water in order to complete their life cycle (Delgadillo, 2003a). They are the second largest group of green plants. They are divided into three groups: hornworts (Class: Anthocerotopsida), liverworts (Class: Hepaticopsida) and mosses (Class: Bryopsida).
They were among the first plant organisms to occupy the terrestrial environment. The name briophyta comes from the Greek Brion, meaning moss and the Latin phyton, meaning plant.
How many are there?
It is estimated that there are about 19,900 described species of mosses (CONABIO 2008). In Mexico, 980 species of mosses and about 500 liverworts are recognized (Delgadillo 1998, 2000, 2003a, b). Of the former group, 106 species (i.e. 10.8%) are endemic to our country (Delgadillo, pers. comm. 2004).
Globally, the mosses are the largest group with around 12,800 species, followed by the liverworts, of which from 6,500 to 7,000 species are known.
However, only about 100 species of hornworts are known.
Where do they live? They live in a wide variety of environments, from high mountain to sea level, in rain forests or in dry areas. Often found in the wetter microclimates of these environments as they require water for reproduction.