Potamogetonaceae, commonly referred to as the pondweed family, are an aquatic family of monocotyledonous flowering plants. There are roughly 120 species spread across six genera. The largest genus in the family by far is Potamogeton, which contains about 100 species.

The family has a sub-cosmopolitan 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.^[1]

Taxonomy

Potamogetonaceae are currently placed in the early diverging monocot order Alismatales by the Angiosperm Phylogeny Group.^[2] 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 six genera: Althenia, Groenlandia, Lepilaena, Potamogeton, Stuckenia, and Zannichellia,^[3] totalling about 120 species of perennial aquatic plants.

Characteristics

The plants are all aquatic perennial herbs, often with creeping rhizomes and leafy branches. Their leaf blades can be either floating or submersed, 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 1-4 drupelets or achenes.^[4]

Genera

• Althenia
• Groenlandia
• Lepilaena
• Potamogeton
• Stuckenia
• Zannichellia

References

1. ^ Haynes, R. R. 1975. A revision of North American Potamogeton subsection Pusilli (Potamogetonaceae). Rhodora 76: 564--64
2. ^ Angiosperm Phylogeny Group. (2009). An update on the angiosperm phylogeny group classification for the orders and families of flowering plants: APG III. Bot J. Linn. Soc. 161: 105-121. http://swepub.kb.se/bib/swepub:oai:DiVA.org:su-36155?tab2=abs&language=en
3. ^ Nunes, E.L.P., de Lima, M.C., Coan, A.I., de Chiara Moco, M.C. (2010). Contribution to the embryology of Potamogeton L. (Alismatales, Potamogetonaceae). Aquatic Botany, 93: 32-38.
4. ^ Watson, L., and Dallwitz, M.J. (1992 onwards). The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 21st March 2010. http://delta-intkey.com/angio/www/potamoge.htm