Dorsiventral describing a structure that has distinct upper and lower surfaces . a dorsiventrally flattened structure has flat dorsal and ventral surfaces and very narrow lateral surfaces 异面（背腹型） :指上下表面结构具有明显差异。异面平滑结构指有平滑的背、腹面，以及非常狭窄的侧表面。
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Like thallose liverworts , the hornworts have an alternation of generations in which the gametophyte is a dorsiventral flattened green phallus and the saprophyte is an upright structure that has a foot embedded in the gametophytes , from which it draws nutrition 与叶状体植物地钱一样，角苔具有明显的世代交替， ，配子体在世代交替中占优势，孢子体占劣势且利用其基足插入配子体的组织中吸取养料，以供孢子体生长。
