The plant body of a liverwort is thalloid. The thallus is dorsiventral and closely appressed to the substrate. The leafy members have tiny leaf-like appendages in two rows on the stem-like structures. Asexual reproduction in liverworts takes place by fragmentation of thalli, or by the formation of specialized structures called gemmae (sing. gemma). During sexual reproduction, male and female sex organs are produced either on the same or on different thalli.