liverwort, any plant of the class Marchantiopsida. Mosses and liverworts together comprise the division Bryophyta, primitive green land plants (see moss; plant); some of the earliest land plants resembled modern liverworts. In contrast to mosses, most liverworts grow prostrate and consist of a flattened, branching (but undifferentiated) green structure, the thallus; other liverworts produce leafy stems, which are flattened and usually prostrate. The ancients believed that liverworts could cure diseases of the liver, hence the name. They are also called hepatics, and the unrelated flowering plant hepatica is frequently called liverwort. Liverworts are classified in the division Bryophyta, class Marchantiopsida.