One of the two subclasses of liverworts (class Hepaticopsida). The gametophytes are ribbonlike or rosette-shaped thalli, usually showing considerable internal tissue differentiation. The rhizoids may be both smooth and internally pegged on the same thalli. Oil bodies, if present, are restricted to scattered cells that lack chloroplasts. The antheridia are usually ovoid, and the archegonia usually consist of six rows of cells. The sporophytes are generally reduced.