Ulva

Green algae, which is named for their grass-green chloroplasts, include unicellular and colonial species as well as multicellular seaweeds. Ulva, or sea lettuce, is a multicellular green algae. Like many multicellular algae and all land plants, Ulva has a complex life cycle that includes an alternation of generations. In this type of life cycle, a multicellular diploid form alternates with a multicellular haploid form. Multicellular diploid forms are called sporophytes, because they produce spores. The sporophyte generation alternates with a haploid generation that features a multicellular haploid form called a gametophyte, which produces gametes. In Ulva, the gametophyte and sporophyte organisms are identical in appearance, although they differ in chromosome number. The haploid gametophyte produces gametes by mitosis, and fusion of the gametes begins the sporophyte generation. In turn, cells in the sporophyte undergo meiosis and produce haploid, flagellated spores. The life cycle is completed when a spore settles to the bottom of the ocean and develops into a gametophyte. -Biology book page 336

 

http://www.anselm.edu/homepage/jpitocch/genbi101/16_20cUlvaLifeCycle-L%20copy.jpg