The mosses, hornworts and liverworts all come under the general classification of 'bryophytes'.
They are usually considered the simplest of those organisms that are actually included in the Plant Kingdom.
They are usually only a few cells thick in structure, and have no efficient system of controlling or moving water within or without their body, as do all the other higher vascular plants.
Thus bryophytes can only grow in very moist places. In the Australian tropical rainforest they can be seen on rocks and logs, often in gullies and around creeks.
While they are common here, they appear to be even more dominant in cooler rainforests, such as those of the Atherton Tablelands and even more so in the temperate rainforests further south, such as in Tasmania.
There are some 950 species so far recorded in Australia, with about 400 of them found in North Queensland (Jackes and Cairns 2001).
From a distance, bryophytes appear only as a carpet of soft green moss.
Close up, they look like tiny individual plants. Generally, they all have small green leaves, above which they project a sporophyte (above left), which consists of a stalk with a container at the end that releases spores.
A closer look can reveal differences that can distinguish between the main groups.
'Mosses' tend to have a series of small spirally arranged leaves, which are usually a little pointy (left).
'Hornworts' have a larger leaf at the base and their common name comes from their double pointed horn-like sporophyte.
The 'liverworts' are either 'leafy' or 'thallose'.
The first tend to look similar to moss with a series of small leaves, but they are arranged in one plane, and roughly opposite each other (in the left hand corner of the picture).
The 'thallose liverworts' tend to have single larger leaves at the base like Hornworts, but have a cup-shaped capsule at the end of their sporophyte.
Script: Courtesy of Damon Ramsey BSc.(Zool) Biologist Guide