Mosses are simple plants with no differentiated parts i.e. leaves, stems, roots. They are multicellular and do not possess a cuticle or stomata except in the spore forming parts. Their features are adapted to moist conditions and vulnerable in dry conditions.
Rhizoids are specialised for attachment to the soil. They do not penetrate deeply, so mosses only populate areas where water and ions are abundant higher in the soil.
Since bryophytes do not posses a vascular system, the structural support is given solely by the turgor pressure inside cells.
The capsule contains spores that disperse to give rise to further plants. Spores germinate in moist conditions, and can withstand a limited amount of desiccation. This renders them vulnerable in dry areas. Mosses are therefore restricted to moist areas.