An order of the liverwort subclass Marchantiidae. Characteristic features include the differentiation of upper and lower tissues of the gametophyte, ventral scales, and rhizoids of two kinds. The sporophyte is considerably reduced, and the capsule dehisces irregularly. The archegonia, though dorsal, come to be pendant from an elevated receptacle because of differential growth resulting in decurved margins. The stalks of the receptacles are modified branches often with rhizoids in one, two, or rarely four furrows along their length. The order consists of 12 families grouped in two suborders, the more complex Marchantiineae and the simplified Ricciineae.