Species may be either monoicous or dioicous. They may be monoicous or dioicous. The states of being monoicous or dioicous are called monoicy and dioicy respectively. Most plants are dioicous except for "U. phyllantha", which is monoicous. The exact arrangement of the antheridia and archegonia in monoicous plants varies. Liverwort species may be either dioicous or monoicous. As an illustration, consider a monoicous moss. These terms occasionally may be used instead of "monoicous" and "dioicous" to describe bryophyte gametophytes. Monoicous plants are necessarily hermaphroditic, meaning that the same plant has both sexes. In monoicous (also called autoicous) mosses, both are borne on the same plant. Mosses can be either dioicous (compare dioecious in seed plants) or monoicous (compare monoecious). Other distinguishing features of "Ulota" include being monoicous, and the absence of asexual reproductive structures. Plants are usually monoicous, and sexual reproduction is by antheridia and archegonia.