When spores are mature, the lid of the capsule, called the operculum, opens, and a row or rows of hygroscopic teeth, the operculum, respond to changes of humidity to open and release spores. Each spore germinates and divides to form a filamentous protonema , which develops into the gametophyte. A common genus is Marchantia , one which has lobes with a central notch and lengthwise surface groove. The meristem is located at the notch, and branching occurs forming two new lobes. All liverworts exhibit the basic alternation of generations.
Meiosis produces half male and half female spores, so that a gametophyte is either male or female.
In Marchantia , for example, the archegonia and the antheridia are elevated above their respective thallus structures on stalks called archegoniophores and antheridiophores. Several archegonia and antheridia are found in each stalk. Other thallose liverworts will have the antheridia and archegonia embedded in the thallus tissue, rather than on stalks. The sporophyte is a simple club-shaped sporangium which grows from a basal foot embedded in the archegonium. At maturity, the sporangium splits open, and the release of spores is assisted by special hygroscopic hairs, called elaters.