Ab
†Abacella Maslov, 1956
- †Abacella pertusa Maslov, 1956c
Plantae → Chlorophyta → Ulvophyceae → Bryopsidales → Codiaceae
Ac
- Acanthocodium
- Acanthoporella
Acanthosphaera Lemmermann, 1899
- Acanthosphaera zacharaisi Lemmermann
Chlorophyta → Chlorophytina → Trebouxiophyceae → Chlorellales → Chlorellaceae
- Acetabularia J.V.Lamouroux, 1812
†Acicularia A. d'Archiac, 1843
- Acicularia cornigera L.Morellet & J.Morellet, 1922 †
- Acicularia pavantina d'Archiac, 1846 †
Chlorophyta → Chlorophytina → Ulvophyceae → Dasycladales → Dasycladaceae
†Aciculella Pia in Hirmer, 1927
- Aciculella bacillum Pia
- Aciculella ogilvie-gordonae G.F.Elliott
- Aciculella preromangica (Praturlon) E.Ott
Chlorophyta → Chlorophytina → Ulvophyceae → Dasycladales → Dasycladaceae
- Acracladus
- Acroblaste Reinsch, 1879
- Acrochasma Korshikov
- Acroporella A.Praturlon
- Acrosiphonia J.Agardh, 1846
- Acrosiphoniales
- Actidesmium Reinsch, 1875
- Actinastrum Lagerheim, 1882
- Actinochloridaceae
- Actinochloris Korshikov, 1953
- Actinoporella C.W.Gümbel
- Actionoporella
- Acutodesmus (Hegewald) Tsarenko, 2001
Ae
- Aegagropila Kützing, 1843
- Aegagropilopsis Boedeker, 2012
- Aerosphaera Gerneck, 1907
Af
- Afghanopolia Kaever
Ag
- Agardhia
- Agardhinella Gaillon
- Agloë Pascher, 1912
Ah
- Ahnfeldtia
Al
- Allodorina De Fromentel
- Altochara Saidakovsky
Am
- Amicus J.P.Maslov
- Amphikrikos Korshikov, 1953
- Amphoraemonas A.Szabados, 1948
An
- Anadyomenaceae Kützing, 1843
- Anadyomene J.V.Lamouroux, 1812
- Ancestria
- Andrusoporella J.Bystrick
- Angioporella M.A.Masse, M.A.Conrad & R.Radoicic
Angulomonas Skvortzov, 1968
- Angulomonas stagnalis Skvortzov
- Angulomonas triquetra Skvortzov
Plantae → Chlorophyta → Prasinophyceae → Pyramimonadales → Pyramimonadaceae
- Anisoporella G.Botteron
- Ankistrodesmaceae Korshikov, 1953
- Ankistrodesmopsis F.Lederer & J.Lukavski, 1998
- Ankistrodesmus Corda, 1838
- Ankyra Fott, 1957
Anthocodium Suringar, 1867
- Anthocodium fragile Suringar
Chlorophyta → Ulvophyceae → Bryopsidales → Codiaceae
- Anthracoporella Pia
- Anthracoporellopsis Maslov
- Anticomonas Skvortzov, 1971
- Antracoporellopsis
Ap
- Apatococcus F.Brand, 1925
- Aphanochaetaceae Oltmanns, 1904
- Aphanochaete Braun, 1851
- Apiochloris Pascher, 1930
- Apiococcus Korshikov, 1926
- Apiocystis Nägeli, 1849
Apjohnia Harvey, 1855
- Apjohnia laetevirens Harvey
- Apjohnia scoparia (Kützing) Valet, 1997
Chlorophyta → Ulvophyceae → Siphonocladales → Siphonocladaceae
- Apodochloris Komárek, 1959
- Apodococcus F.Hindák, 1984
Ar
- Arabicodium
- Arabicodium G.F.Elliott, 1957
- Archaeocladus Endo
- Argillamonas Skvortzov, 1971
- Arnoldiamonas Skvortzov, 1969
- Arnoldiella V.V.Miller, 1928
- Arthrochaete Rosenvinge, 1898
- Arthrorhabdium Ehrenberg
As
- Ascidiella L.Grambast
- Ascidium Braun
- Ascochloris H.C.Bold & F.J.MacEntee, 1974
- Askenasyella Schmidle
- Asphaltinella B.Mamet & A.Roux, 1978
- Asterarcys A.Comas Gonzales, 1981
- Astericium
- Asteriscium Corda
- Asterochloris Tschermak-Woess, 1980
- Asterococcus Scherffel, 1908
- Asterodictyon Ehrenberg
- Asteromonadaceae
- Asteromonas A.Artari, 1913
- Asteroxanthium Kützing
- Astrephomene Pocock, 1954
- Astrocladium Tschourina, 1909
At
- Atopochara Peck
- Atractinium Zacharias
- Atractomorpha L.Hoffman, 1983
- Atractyliopsis Pia
Au
- Aulacomonas Skuja, 1939
- Auxenochlorella (I.Shihira & R.W.Krauss) T.Kalina & M.Puncochárová, 1987
Av
- Avrainvillea Decaisne, 1842
Ax
- Axilococcus T.R.Deason & W.R.Herndon, 1989