The Potamogetonaceae, commonly referred to as the pondweed family, is an aquatic family of

monocotyledon Monocotyledons (), commonly referred to as monocots, (Lilianae ''sensu'' Chase & Reveal) are grass and grass-like flowering plants (angiosperms), the seeds of which typically contain only one embryonic leaf, or cotyledon. They constitute one of ...

ous

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

s. The roughly 110 known species are divided over six genera. The largest genus in the family by far is ''

Potamogeton ''Potamogeton'' is a genus of aquatic, mostly freshwater, plants of the family Potamogetonaceae. Most are known by the common name pondweed, although many unrelated plants may be called pondweed, such as Canadian pondweed (''Elodea canadensis'' ...

'', which contains about 100 species. The family has a sub

cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext ...

, and is considered to be one of the most important

angiosperm Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

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 The Alismatales (alismatids) are an order of flowering plants including about 4,500 species. Plants assigned to this order are mostly tropical or aquatic. Some grow in fresh water, some in marine habitats. Description The Alismatales compri ...

by the Angiosperm Phylogeny Group. Their concept of the family includes the plants sometimes treated in the separate family

Zannichelliaceae 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 six genera. The largest genus in the family by far is ''Potamogeton'', w ...

, but excludes the genus ''

Ruppia ''Ruppia'', also known as the widgeonweeds, ditch grasses or widgeon grass, is the only extant genus in the family Ruppiaceae, with eight known species. These are aquatic plants widespread over much of the world. The genus name honours Heinrich ...

''. So circumscribed, the family currently consists of six genera: ''

Althenia ''Althenia'' is a genus of aquatic plants of the family Potamogetonaceae. This has long been a group of two species in the Mediterranean Europe and South Africa, but in 2016 was revised to include an Australasian relative, ''Lepilaena''. Descri ...

'', ''

Groenlandia ''Groenlandia'' is a monotypic genus of aquatic plants (pondweed) of the family Potamogetonaceae. The only species in the genus is ''Groenlandia densa''. Opposite-leaved pondweed is a common name for this plant. It is native to much of Europe, w ...

'', ''

Lepilaena ''Althenia'' is a genus of aquatic plants of the family Potamogetonaceae. This has long been a group of two species in the Mediterranean Europe and South Africa, but in 2016 was revised to include an Australasian relative, ''Lepilaena''. Descri ...

'', ''

Stuckenia ''Stuckenia'' is a genus of flowering aquatic plants. It contains approximately 30 species that grow in shallow water. Pondweed is a common name for plants in this genus. Description These herbs have rhizomes but not turions. Tubers can be absen ...

'', and ''

Zannichellia ''Zannichellia'' (common name horned pondweed) is a genus of submerged aquatic flowering plant, with threadlike leaves and tiny flowers. It is fully adapted to an aquatic life cycle, including underwater pollination. There are perhaps five spec ...

'',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. totalling about 120 species of perennial

aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae and other microphytes. A macrophyte is a plant that ...

s. Marine grasses families:

Zosteraceae Zosteraceae (one of the four seagrasses families, Kubitzki ed. 1998) is a family of marine perennial flowering plants found in temperate and subtropical coastal waters, with the highest diversity located around Korea and Japan. Most seagrasses ...

Cymodoceaceae Cymodoceaceae is a family of flowering plants, sometimes known as the "manatee-grass family", which includes only marine species. The 2016 APG IV does recognize Cymodoceaceae and places it in the order Alismatales, in the clade monocots. The fam ...

Ruppiaceae ''Ruppia'', also known as the widgeonweeds, ditch grasses or widgeon grass, is the only extant genus in the family Ruppiaceae, with eight known species. These are aquatic plants widespread over much of the world. The genus name honours Heinrich ...

and

Posidoniaceae ''Posidonia'' is a genus of flowering plants. It contains nine species of marine plants ("seagrass"), found in the seas of the Mediterranean and around the south coast of Australia. The APG system (1998) and APG II system (2003) accept this gen ...

. Related families: Potamogetonaceae,

(not consistently).

Characteristics

The plants are all aquatic

perennial A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wide ...

herbs, often with creeping

rhizome In botany and dendrology, a rhizome (; , ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...

s and leafy branches. Their

leaf A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, ste ...

blades can be either floating or submerged, and their stems are often joined. No

stomata In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is bor ...

are present on the leaves. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are tetramerous: the floral formula (sepals; petals; stamens; carpels) is ;0;4;4 The flowers have no petals. The

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

consists of one to four

drupelet In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...

s or

achene An achene (; ), also sometimes called akene and occasionally achenium or achenocarp, is a type of simple dry fruit produced by many species of flowering plants. Achenes are monocarpellate (formed from one carpel) and indehiscent (they do not ope ...

s.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

Genera

*''

'' *''

'' *'' Pseudalthenia'' *''

'' *''

References

External links

Angiosperm Phylogeny Website
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 {{Authority control Alismatales families Aquatic plants