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 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:[1]
AlgaeBase places the genus Nitellopsis, which has both extant and extinct species, in the family Feistiellaceae.[4] Other sources place Nitellopsis in the family Characeae,[5] with Feistiellaceae containing only fossil species,[6] so that all extant species are in the family Characeae. The Interim Register of Marine and Nonmarine Genera accepts a further three extinct families:[3]
Body fossils of representatives of the order Charales do exist, but are rare.[7] The fossil record of the Charales consists mostly of gyrogonites, that is, calcified fructifications or, more exactly, calcified spiral cells surrounding the oospores. It may be noted that the gyrogonites are studied by palaeontologists, but not often destroyed (using acids) during neontological research to liberate the oospores.[8]
The oldest known representative of the Charales is Eochara wickendenii Choquette from the Middle Devonian.[9] The family Characeae starts dominating the fossil assemblages in the Paleogene or perhaps already in the Late Cretaceous.[10]
^Feist, Monique (2005). Treatise on Invertebrate Paleontology, Part B: Protoctista 1, Volume 1: Charophyta. Boulder, Colorado–Lawrence, Kansas: Geological Society of America–University of Kansas. ISBN0-8137-3002-3.
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. ISBN978-1-904890-31-7.
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.