(wracks) The only order of the Cyclosporae, a subclass of the * Phaeophyta. It consists solely of marine forms with the commoner species (e.g. Fucus, Pelvetia, Ascophyllum) making up a large proportion of the vegetation of the coastal littoral zone. The thallus is differentiated into holdfast and lamina and often contains air bladders. Reproduction is oogamous with the gametangia developing in specialized invaginations, the * conceptacles. There is no alternation of generations, the * life cycle being diplontic. |
