The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of monocotyledonous flowering plants. The roughly 110 known species are divided over five genera. The largest genus in the family by far is Potamogeton, which contains about 100 species.

The family has a subcosmopolitan distribution, and is considered to be one of the most important angiosperm groups in the aquatic environment because of its use as food and habitat for aquatic animals.Haynes, R. R. 1975. A revision of North American Potamogeton subsection Pusilli (Potamogetonaceae). Rhodora 76: 564--64

Taxonomy

The Potamogetonaceae are currently placed in the early diverging monocot order Alismatales by the Angiosperm Phylogeny Group. Their concept of the family includes the plants sometimes treated in the separate family Zannichelliaceae, but excludes the genus Ruppia. So circumscribed, the family currently consists of five genera totalling about 120 species of perennial aquatic plants. Althenia Groenlandia Potamogeton Stuckenia Zannichellia

Marine grasses families: Zosteraceae, Cymodoceaceae, Ruppiaceae and Posidoniaceae. Related families: Potamogetonaceae, Zannichelliaceae (not consistently).

+ Families and Genera crosses (Sea grasses) Kubitzki (ed. 1998Kubitzki (ed.) 1998. The families and genera of vascular plants, vol 4, Monocotyledons: Alismatanae and Commelinanae (except Gramineae). Springer-Verlag, Berlin.) Watson & Dallwitz (delta-intkey)Watson & Dallwitz. Zosteraceae. The families of flowering plants. http://delta-intkey.com/angio/www/zosterac.htm data.kewVascular Plant Families and Genera. List of genera in family CYMODOCEACEAE (accessed 2016-06-02) http://data.kew.org/cgi-bin/vpfg1992/genlist.pl?CYMODOCEACEAE APWeb (mobot.org)VASCULAR PLANT FAMILIES and GENERA. List of Genera in CYMODOCEACEAE (accessed 2016-06-02) http://www.mobot.org/mobot/research/apweb/orders/alismatalesweb.htm#Cymodoceaceael Zosteraceae 1. Zostera L. Zostera Zostera L. Zostera L. (including Heterozostera den Hartog, Macrozostera Tomlinson & Posluzny, Nanozostera Tomlinson & Posluzny, Zosterella J. K. Small) 2. Heterozostera den Hartog Heterozostera Heterozostera (Setch.) Hartog (in Zostera) 3. Phyllospadix Hook. Phyllospadix Phyllospadix Hook. Phyllospadix J. D. Hooker Cymodoceaceae 1. Syringodium Kütz Syringodium Syringodium Kutz. (in Cymodocea) 2. Halodule Endl. Halodule Halodule Endl. Halodule Endlicher 3. Cymodocea König Cymodocea Cymodocea K.Koenig (including Phycoschoenus (Asch.) Nakai ) Cymodocea König (including Amphibolis Agardh ?, Syringodium Kütz. ?, Thalassodendron den Hartog ?) 4. Amphibolis Agardh Amphibolis Amphibolis C.Agardh (including Pectinella J.M.Black) (in Cymodocea) 5. Thalassodendron de Hartog (name not found) Thalassodendron Hartog (in Cymodocea) Ruppiaceae Ruppia L. Ruppia (in Ruppia L. in Potamogetonaceae) Ruppia L. Posidoniaceae Posidonia König Posidonia Posidonia K.Koenig Posidonia König

+ Families and Genera crosses (Potamogetonaceae) Kubitzki (ed. 1998) Watson & Dallwitz (delta-intkey)Watson & Dallwitz. Potamogetonaceae. The families of flowering plants. http://delta-intkey.com/angio/www/potamoge.htm data.kewVascular Plant Families and Genera. List of genera in family POTAMOGETONACEAE (accessed 2016-06-02) http://data.kew.org/cgi-bin/vpfg1992/genlist.pl?POTAMOGETONACEAE APWeb (mobot.org)VASCULAR PLANT FAMILIES and GENERA. List of Genera in POTAMOGETONACEAE (accessed 2016-06-02) http://www.mobot.org/mobot/research/apweb/orders/alismatalesweb.htm#Potamogetonaceae Potamogetonaceae 1. Potamogeton L. Potamogeton Potamogeton L. Potamogeton L. (including Coleogeton Les & Haynes, Stuckenia Börner) 2. Groenlandia J. Gray Groenlandia Groenlandia J.Gay Groenlandia J. Gay (in Ruppia in Ruppiaceae) (in Ruppia in Ruppiaceae) Ruppia L. (in Ruppia in Ruppiaceae) (in Althenia: Zannichelliaceae and Lepilaena: Zannichelliaceae) (in Althenia: Zannichelliaceae and Lepilaena: Zannichelliaceae) (in Althenia F.Petit: Zannichelliaceae and Lepilaena J.L.Drumm. ex Harv.:Zannichelliaceae) Althenia Petit (including Lepilaena Harvey) (in Pseudalthenia including Vleisia: Zannichelliaceae) (in Pseudalthenia: Zannichelliaceae and Vleisia: Zannichelliaceae) (Pseudalthenia not found, Vleisia Toml. & Posl.: Zannichelliaceae) Pseudalthenia Nakai (including Vleisia Tomlinson & Posluszny) (in Zannichellia L.: Zannichelliaceae) (in Zannichellia: Zannichelliaceae) (in Zannichellia L.: Zannichelliaceae) Zannichellia L. Zannichelliaceae 1. Zannichellia L. Zannichellia Zannichellia L. (in Zannichellia L.: Potamogetonaceae) 2. Pseudalthenia Nakai (including Vleisia) Pseudalthenia (excluding Vleisia) (name not found) (in Pseudalthenia: Potamogetonaceae) 3. Althenia Petit (excluding Lepilaena Drumm. ex. Harv.) Althenia (excluding Lepilaena) Althenia F.Petit (excluding Lepilaena J.L.Drumm. ex Harv.) Althenia Petit (including Lepilaena Harvey) 4. Lepilaena Drumm. ex. Harv. Lepilaena Lepilaena J.L.Drumm. ex Harv. (in Althenia Petit) (in Pseudalthenia) Vleisia Vleisia Toml. & Posl. (in Pseudalthenia: Potamogetonaceae)

Characteristics

The plants are all aquatic perennial herbs, often with creeping rhizomes and leafy branches. Their leaf blades can be either floating or submerged, and their stems are often joined. No stomata are present on the leaves. The flowers are tetramerous: the floral formula (sepals; petals; stamens; carpels) is [4;0;4;4]. The flowers have no petals. The fruit consists of one to four drupelets or achenes.Watson, L., and Dallwitz, M.J. (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 21 March 2010. http://delta-intkey.com/angio/www/potamoge.htm

References

External links Angiosperm Phylogeny Website Potamogetonaceae at the DELTA Online Families of Flowering Plants Potamogetonaceae at the Germplasm Resources Information Network Potamogetonaceae at the Online Flora of North America Zannichelliaceae at the Online Flora of North America Potamogetonaceae at the NCBI Taxonomy Browser