There are two groups of
bryophyta (see
Plant Kingdom). One of them is Mosses which represent an evolutionary step up from
algae. They are simple green land plants with leaves and a stem and always without roots.
In many mosses, the leaves are only one cell thick, except for the midribs, which are sometimes present. The plant is normally attached to the ground by delicate, colourless or brown threads, the rhizoids.
Most mosses are found in areas with a humid and a cold to moderate warm climate. In the tropics, mosses are found especially in the mountains. In Europe, the south western part of Ireland is a paradise for mosses.
Mosses can reproduce asexually, by means of small clusters of cells or plates of tissue which break away and germinate to become new plants. Especially liverworts do this. It is believed by scientists that as the first land plants, mosses probably created the first forests, mini-ecosystems just 5cm or so high.