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This survey of the order Marchantiales contains descriptions of the order and of the genera including morphological, ontogenetic and cytological characters, reassessed with living plant material, ecological data, life history traits, geographical distributions and keys, as well as an outline of published evolutionary classifications and scenarios based on morphological, phytochemical and molecular sequence data. The relationships of the order with the other liverwort orders, with the mosses and with the land plants are summarized. The phylogenetic reconstruction does not confirm most of the assumptions on evolution based on phytochemical data, or on molecular sequence data, sampled at present for only a small number of species. In the future, alanysis of other, especially ontogenetic, data and more complete sets of phytochemical and molecular sequence data will be necessary to test the robustness of the proposed phylogenetic hypothesis. A critical reevaluation of morphological characters might then be within reach.