Mosses and liverworts are some of the many organisms found in Arches that most people do not associate with deserts. Mosses can tolerate long periods of complete dehydration and occupy a variety of habitats in the park, including exposed rocks, cryptobiotic soil crusts, riparian areas and sometimes trees. They do best in shady canyons, north-facing slopes and at the bases of shrubs. Most liverworts must be near water to survive, and are very rare in the park.

Mosses and liverworts are small, primitive, non-vascular plants. They lack the conductive tissue most plants use to transport water and nutrients. Instead, moisture is absorbed directly into cells by osmosis. The most abundant mosses in Arches can remain dry for years, and will rehydrate in seconds after contact with water. Some species begin photosynthesizing less than one hour after being moistened.

There is no complete inventory of mosses and liverworts in Arches. At least 20 moss species are known to colonize cryptobiotic soil crusts, with Syntrichia caninervis being the most common. Grimmia orbicularis accounts for 80 percent of the moss found on rock surfaces.

Like all photosynthetic organisms, mosses are primary producers that build biomass through photosynthesis. They enrich ecosystems with organic matter, forming the basis of the food chain. As a component of cryptobiotic soil crusts, mosses trap airborne soil particles, reduce erosion, retain water and may enhance water infiltration.