Liverwort, the common name for a class of rather primitive plants. Liverworts grow chiefly in damp soil and on trees and logs. Some are adapted to growing on rocks, and a few grow in water. Liverworts do not have roots, stems, leaves, flowers, fruits, or seeds. Instead of roots they have hairlike rhizoids that anchor them and absorb moisture. Liverworts are seldom more than four inches (10 cm) in length and half an inch (13 mm) in width. The plants are of little economic value.
Thallose liverworts have thin, flat bodies, called thalluses, that lie flat against the surfaces on which they grow, forking and reforking as they spread. The thallus is commonly shaped like the human liver, giving the plant its name. (Wort means “plant.”) Tiny cups on the surface of the thallus bear disk-shaped buds called gemmae, or gemmules. Each gemma can grow into a new plant. In some species, there are separate male and female plants, each bearing male or female reproductive organs consisting of disks supported by stalks.
Foliose, or leafy, liverworts have structures that resemble leaves and stems, but these growths lack the tissues of true leaves and stems. Foliose liverworts look like mosses, but they are flat instead of upright in growth, and the shoots bear rhizoids on their undersides. They produce gemmae on the leaflike structures.
Liverworts can reproduce by either of two methods: (1) asexually (as by gemmae) and (2) by alternation of generations, in which one generation is produced sexually and the next by spores.
Liverworts make up the class Hepaticae of the division Bryophyta.