The mosses are a major division of the Plantae Kingdom. They are non-vascular and absorb water through their leaves. They do not have flowers or seeds, but propagate using spores. They are typically small (less than 10cm tall), soft, and grow in clumps or mats. They generally require moist environments to aid water absorption.
Historically, Bryophyta have included liverworts and hornworts but these are now classified in their own divisions.
Mosses can become a weed in lawns which are too moist, and in extreme cases (eg. parts of the Pacfic Northwest) it is deliberately encouraged as a lawn substitute which requires little mowing, fertilizer, or water.
Moss is also deliberately grown in Japanese styles of gardening where moss can add a sense of calm, age, and stillness. Moss is also used with bonsai to cover the soil and enhance the general impression of extreme age.
Mosses are also sometimes used in green roofs where they are useful for their reduced weight loads and no fertilizer requirements.
Use this tag for all gardening questions about moss, whether it is discouraging lawn grown, encouraging lawn growth, or its use in bonsai.