Chara species are filamentous, mat forming green algae. They can be recognised by their whorls of simple branchlets, general stiffness and/or calcification. Wood (1967) describes grey stonewort as: a small, spiny looking Chara of saline or brackish water; commonly less than 8 inches, which forms dense carpets in shallow water; it may be monoecious or dioecious, with monoecious plants widespread within its range in North America, and dioecious plants restricted to coastal areas in New England and British Columbia. Proper identification of Chara species is dependent on features of the stem and reproductive structures, and usually requires microscopic work.