![Elodea nuttallii-female flower](https://upload.wikimedia.org/wikipedia/commons/d/db/Elodea_nuttallii-female_flower.jpg)
''Elodea nuttallii'' is a species of
waterweed
''Elodea'' is a genus of 6 species of aquatic plants often called the waterweeds described as a genus in 1803. Classified in the frog’s-bit family (Hydrocharitaceae), ''Elodea'' is native to the Americas and is also widely used as aquarium vege ...
known by the common name western waterweed or Nuttall's waterweed.
This is a perennial
aquatic plant which is native to North America where it grows submersed in lakes, rivers, and other shallow water bodies. It is also found in Eurasia, where it is commonly
weedy; it is not known as a weed species in its native range. It is sometimes used as an
aquarium plant.
Description
It is similar to its relative, ''
Elodea canadensis''. However, the leaves taper to an acute point. It has a thin branching stem with whorls of flat leaves at intervals. Some leaves are recurved and twisted, with minute teeth. It bears tiny flowers, the
staminate
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
ones
abscissing from their stalks and floating away from the plant. It flowers from May until October.
In Europe nearly all individuals are female, only some places with male plants are known.
Distribution
This species is native to temperate North America. It has been naturalised in Europe since 1939 and in Japan since the 1960s.
[ The first European record of ''Elodea nuttallii'' was probably 1914 in England, though it had been identified wrongly as '']Hydrilla verticillata
''Hydrilla'' (waterthyme) is a genus of aquatic plant, usually treated as containing just one species, ''Hydrilla verticillata'', though some botanists divide it into several species. It is native to the cool and warm waters of the Old World in ...
'', with correct identification as ''Elodea nuttallii'' occurring in 1974. It seems to have been originally naturalised in Oxfordshire in 1966, but has now spread to most of England, and many parts of lowland Wales and lowland Scotland. The first record in Ireland was in Lough Neagh in 1984, and it has now spread widely in the country. It is an invasive species in Europe; it reached Belgium in 1939, the Netherlands in 1941, Germany in 1953, Denmark in 1974, Sweden in 1991 and Norway in 2006. It is now present in most of Northern Europe, in many parts displacing the invasive ''Elodea canadensis''.
References
External links
Jepson Manual Treatment
{{Taxonbar, from=Q158887
Hydrocharitaceae
Freshwater plants
Flora of North America
Flora of Europe
Flora of Asia
Plants described in 1848