Cutleriales

an order of brown algae of the group Isogenerataephyceae. The thallus may be as much as 10 cm tall; lamellate, vertical, or corticiform; and entire, divided into lobes, or fan-shaped. It consists of several layers of large colorless cells, which are covered by one or more layers of small pigmented cells of the cortex. The edges of the thallus are fringed with multicellular hairs.

The growth of Cutleriales is trichothallic—that is, through division of the cells in the bases of the hairs. Reproduction is sexual (heterogamy; multilocular gametangia) and asexual (zoospores, whose formation in unilocular sporangia is accompanied by meiosis). The gametangia and sporangia are formed on different plants, which may be externally similar (Zanardinia) or different (Cutleria). In Cutleria the gametophyte is erect and annual; the sporophyte is corticiform and perennial (its sporo-phyte was earlier believed to be a separate genus).

Three genera of Cutleriales are known, including some species that grow in warm seas. There is one species of Zanardinia in the USSR (in the Black Sea).