About 130 species of bryophytes have been recorded from Antarctica. These are divided amongst the mosses (100 species) and the hepatics, or liverworts, (25–30 species). They typically appear as small leafy plants, either upright or creeping.
Like the lichens, the bryophytes can be found in almost all areas capable of supporting plant life in the Antarctic, though they are not as widespread. Moss lawns often occur on meltwater flushes from ponds, such as at Casey station, or from glaciers, such as the Canada Glacier in Southern Victoria Land.
Mosses have been collected from as far south as 84°30’ — Ceratodon purpureus at Mt. Kyffin, Southern Victoria Land.
The dominant stage in the life cycle of bryophytes is the sexually reproducing gametophyte plant stage. However due to the extreme environmental conditions under which these plants exist, most reproduction occurs asexually from a deciduous shoot apex or other specialised asexual reproductive structures, called gemmae. Sexual reproductive structures may be present on the gametophyte, although male and female organs are rarely found on the same plant. In many cases the sporophyte stage, produced after sexual reproduction, is completely absent amongst Antarctic bryophytes. This is more often true for the bryophytes of the Continental Antarctic, where only about 25% of moss species produce a sporophyte stage. In the Maritime Antarctic approximately 30% of moss species produce a sporophyte stage.
The bryophytes exhibit a number of adaptations to the Antarctic environment. Many of the mosses have tightly packed stems and shoots to minimise water loss. Some mosses have orange carotenoid pigments which may help prevent photosystem damage during the growing season. Snow cover is important in protecting plants from wind, windblown ice and sand particles and extremes of temperature. If the protective cover of snow is removed then photoinhibition can occur, dramatically decreasing growth rates.
The impact of climate change is a major research topic of interest in the Antarctic terrestrial ecosystems, particularly the impact on bryophytes. Temperature, UVB, water availability and exposure to wind are key factors that are changing in various ways in different locations. Temperatures on the Antarctic peninsula are rising at some of the fastest rates on the planet.
Bryophytes are also quite sensitive to atmospheric pollution from distant sources. Traces of DDT and organochlorines have been detected in Antarctic bryophytes. Radionuclides, possibly of anthropogenic origin, have also been shown to accumulate in Antarctic bryophytes, lichens, algae, and soil.