Abstract:

In the present study the authors observed and reported the morphological characters and development process in all stages of the life history of Monostroma latissimum Wittrock for the first time in China. The process of parthenogenesis has also been observed in yearly culture. When the dioecious macrogametophytes mature, they liberate biflagellate gametes, and when the spherical microsporophytes mature, they produce quadriflagellate zoospores. Its life history is a periodical heteromorphic alternation of haploid gametophyte generation and diploid sporophyte generation. In addition, this study indicates the multiplication of zygotes and cysts by binary fission, two-year-old cysts compared with gametophytes living for one year in the life history of M. latissimum. The male and female gametes that do not conjugate also undergo parthenogenesis as they adhere to the substrates. They become unicellular bodies, spherical in shape, somewhat smaller than the zygotes. Then, the cysts of parthenogenesis mature and liberate a number of quadriflagellate swarm spores. These spores adhere to substrates and germinate directly into the leaf fronds. As for zygotes, parthenogenesis of the male and female gametes also can be used for artificial seeding of M. latissimum in culture.

Key words: Monostroma latissimum , life history, Chlorophyta