Bryophytes include mosses, liverworts, and hornworts. They are non-vascular plants that lack true roots, stems, or leaves. Bryophytes reproduce both sexually through an alternation of generations involving gametophytes and sporophytes, and asexually through fragmentation or structures like gemmae. The dominant generation is the gametophyte. Mosses commonly grow in dense colonies on soil, rocks, and trees, helping to form soil and prevent erosion. Liverworts have a thallus shape and reproduce using gemmae cups. Hornworts have thalloid bodies and hornlike sporophyte projections. Bryophytes play various ecological roles and some have human uses as well.