Charales is an order of freshwater green algae in the division Charophyta, class Charophyceae, commonly known as stoneworts. Depending on the treatment of the genus Nitellopsis, living (extant) species are placed into either one family (Characeae) or two (Characeae and Feistiellaceae). Further families are used for fossil members of the order. Linnaeus established the genus Chara in 1753.
The higher level classification of green algae was unsettled as of February 2022[update]. AlgaeBase places Charales within the class Charophyceae and its circumscription of the division Charophyta.
The number of families and their division into genera varies. As of February 2022[update], AlgaeBase accepts two families containing some extant species and four families containing only fossil species:
- Characeae S.F.Gray
- Feistiellaceae Schudack
- †Aclistocharaceae X.G.Zhou (may be included in Characeae)
- †Atopocharaceae R.E.Peck (may be included in Clavatoraceae)
- †Clavatoraceae Pia
- †Porocharaceae Grambast
AlgaeBase places the genus Nitellopsis, which has both extant and extinct species, in the family Feistiellaceae. Other sources place Nitellopsis in the family Characeae, with Feistiellaceae containing only fossil species, so that all extant species are in the family Characeae. The Interim Register of Marine and Nonmarine Genera accepts a further three extinct families:
- Guiry, M.D.; Guiry, G.M. "Charales". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 20 February 2022.
- "Classification of algae". Encyclopedia Britannica. Retrieved 20 February 2022.
- "Charales". Interim Register of Marine and Nonmarine Genera (IRMNG). Retrieved 20 February 2022.
- Guiry, M.D.; Guiry, G.M. "Nitellopsis". AlgaeBase. World-wide electronic publication, National University of Ireland, Galway. Retrieved 20 February 2022.
- "Nitellopsis Hy, 1889". Interim Register of Marine and Nonmarine Genera (IRMNG). Retrieved 20 February 2022.
- "Feistiellaceae Schudack, 1993 †". Interim Register of Marine and Nonmarine Genera (IRMNG). Retrieved 20 February 2022.
- Bryant, J. The stoneworts (Chlorophyta, Charales). In Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K. 2007. New Survey of Clare Island. Royal Irish Academy. ISBN 978-1-904890-31-7.
- Schaible, R. and Schubert, H. 2008. The occurrence of sexual Chara canesces populations (Charophyceae) is not related to ecophysiological potentials with respect to salinity and irradiance. Eur. J. Phycol. 43: 309 - 316.
- Desai, Udaysingh and Karande C.T. 2008. "Biodiversity of Charophytes from Kolhapur District, Maharashtra". Shivaji University, Kolhapur.