Liverwort
Liverwort, common name for members of a phylum of bryophytes , a group of usually inconspicuous plants. There are two major liverwort types: thallose liverworts and leafy liverworts. The common name, liverwort, derives from the fact that some thallose are liver-shaped in outline. About 300 genera and 6000 species of liverworts occur throughout the moist temperate to tropical regions. Liverworts are characterized by a free-living, conspicuous, sexual (gametophytic) generation, to which is attached a usually inconspicuous, asexual (sporophytic) generation. The gametophyte may be a leafless, flattened thallus; more often it is leafy, with the leaves produced in three rows, of which one is smaller than the others. The lower surfaces of the gametophytes produce unicellular, rootlike structures called rhizoids, which serve for attachment and external water transport. The sporophytes of liverworts are simple structures consisting of a foot embedded in the gametophyte and a spore-producing cap...