Potamogetonaceae

The Potamogetonaceae, commonly called the pondweed family, are an aquatic household of monocotyledonous flowering plants. The approximately 110 known species are divided over six genera (Christenhusz & Byng 2016). The largest genus in the family by far is Potamogeton, which comprises about 100 species.

The household has a subcosmopolitan distribution and is thought of as among the most significant angiosperm groups from the aquatic environment due to its use as habitat and food for aquatic animals.

Categorization

The Potamogetonaceae are currently placed at the first diverging monocot order Alismatales by the Angiosperm Phylogeny Group. Their concept of the household contains the plants occasionally treated in the individual family Zannichelliaceae, but excludes the genus Ruppia. So circumscribed, the family now includes six genera: Althenia, Groenlandia, Lepilaena, Potamogeton, Stuckenia, and Zannichellia,[4] totalling about 120 species of recurrent aquatic plants.

Marine grasses families: Zosteraceae, Cymodoceaceae, Ruppiaceae and Posidoniaceae. Associated families: Potamogetonaceae and (and sometimes including) Zannichelliaceae.

Characteristics

The plants are aquatic perennial herbs, often with creeping rhizomes and leafy branches. Their leaf blades can be either floating or submerged, and their stalks are often joined. No stomata are found on the leaves. The blossoms are tetramerous: the floral formula (sepals; petals; stamens; carpels) is [4;0;4;4]. The flowers have no petals. The fruit is composed of one to four drupelets or achenes.