Hepaticology

Liverworts Temporal range: 472–0 Ma PreЄ Є O S D C P T J K Pg N Mid-Ordovician to recent
"Hepaticae" from Ernst Haeckel's Kunstformen der Natur, 1904
Scientific classification
Kingdom:	Plantae
Division:	Marchantiophyta Stotler & Stotl.-Crand., 1977 emend. 2000
Classes and Orders
Haplomitriopsida Haplomitriales Treubiales Marchantiopsida Blasiales Neohodgsoniales Sphaerocarpales Lunulariales Marchantiales Jungermanniopsida Pelliales Pallaviciniales Fossombroniales Pleuroziales Metzgeriales Porellales Ptilidiales Jungermanniales

The Marchantiophyta ⁱ/mɑːrˌkæntiˈɒfᵻtə/ are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.

It is estimated that there are about 9000 species of liverworts. Some of the more familiar species grow as a flattened leafless thallus, but most species are leafy with a form very much like a flattened moss. Leafy species can be distinguished from the apparently similar mosses on the basis of a number of features, including their single-celled rhizoids. Leafy liverworts also differ from most (but not all) mosses in that their leaves never have a costa (present in many mosses) and may bear marginal cilia (very rare in mosses). Other differences are not universal for all mosses and liverworts, but the occurrence of leaves arranged in three ranks, the presence of deep lobes or segmented leaves, or a lack of clearly differentiated stem and leaves all point to the plant being a liverwort.