Chara species are filamentous, mat forming green algae. They can be recognised by their whorls of simple branchlets, general stiffness and/or calcification. Common stonewort is a monecious species of charophyte that is commonly found in calcareous freshwater sites (lakes and rivers) where it may grow in thick populations or carpets in shallow water. It can resemble some species of submerged aquatic vascular plants. Although plants are smooth, stems are commonly encrusted in lime. Identification of Chara vulgaris is considered difficult because of great variation in morphology. Wood (1967) states that it has "considerable ecological and great genetic variation". Several forms of Chara vulgaris have been given varietal names. However, these varieties appear to represent ecological plasticity. Proper identification of Chara species is dependent on features of the stem and reproductive structures, and usually requires microscopic work. Wood (1967) maps Chara vulgaris as widespread in the US, Central America, and southern Canada; on the Pacific Coast he maps it as present north through BC to southern Alaska. In British Columbia, it has been collected in the northern part of the province, but it is also present in the south, in lakes such as Cheam Lake near Chilliwack, which is a marl lake. Charophytes, including this species, play a role in the formation of marl and limestone. Chara vulgaris forms part of the diet of Trumpeter Swans.