Elodea canadensis

Taxobox
name = "Elodea canadensis"

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image_width = 240px
regnum = Plantae
divisio = Magnoliophyta
classis = Liliopsida
ordo = Alismatales
familia = Hydrocharitaceae
genus = "Elodea"
species = "E. canadensis"
binomial = "Elodea canadensis"
binomial_authority = Michx.
synonyms = "Anacharis canadensis" (Michx.) Planch.

"Elodea canadensis" (American or Canadian Waterweed or Pondweed) is a perennial aquatic plant, or submergent macrophyte, native to most of North America.Flora of North America: [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=220004673 "Elodea canadensis"] ] Plants of British Columbia: [http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Elodea+canadensis "Elodea canadensis"] ] Jepson Flora: [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?Elodea+canadensis "Elodea canadensis"] ]

Young plants initially start with a seedling stem with roots growing in mud at the bottom of the water; further adventitious roots are produced at intervals along the stem, which may hang free in the water or anchor into the bottom. It grows indefinitely at the stem tips, and single specimens may reach lengths of 3 m or more. The leaves are bright green, 6-17 mm long and 1-4 mm broad, borne in whorls of three (rarely two or four) round the stem. It lives entirely underwater, the only exception being the small white or pale purple flowers which float at the surface and are attached to the plant by delicate stalks. It is dioecious, with male and female flowers on different plants. The flowers have three small white petals; male flowers have 4.5-5 mm petals and nine stamens, female flowers have 2-3 mm petals and three fused carpels. The fruit is an ovoid capsule, about 6 mm long containing several seeds that ripen underwater. The seeds are 4-5 mm long, fusiform, glabrous (round), and narrowly cylindrical.Huxley, A., ed. (1992). "New RHS Dictionary of Gardening". Macmillan ISBN 0-333-47494-5.]

It grows rapidly in favorable conditions and can choke shallow ponds, canals, and the margins of some slow-flowing rivers. It requires summer water temperatures of 10-25 °C and moderate to bright lighting.

It is closely related to "Elodea nuttallii", which generally has narrower leaves under 2 mm broad. It is usually fairly easy to distinguish from its relatives, like the Brazilian "Egeria densa" and "Hydrilla verticillata". These all have leaves in whorls around the stem; however, "Elodea" usually has three leaves per whorl, whereas "Egeria" and "Hydrilla" usually have four or more leaves per whorl. "Egeria densa" is also a larger, bushier plant with longer leaves.Native Freshwater Plants: [http://www.ecy.wa.gov/programs/wq/plants/native/elodea.html American Waterweed] ]

Cultivation and uses

It is frequently used as an aquarium plant. Propagation is by cuttings.Hiscock, P. (2003). "Encyclopedia of Aquarium Plants" Interpret Publishing, United States and Canada ISBN 0-7641-5521-0.]

It is an invasive species in Europe, Asia, Africa, and Australia. It was introduced into County Down, Ireland in about 1836, and appeared in Great Britain in 1841, spreading through both countries in ponds, ditches and streams, which were often choked with its rank growth.Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=4168 "Elodea canadensis"] ]

Other common names for this plant include Anacharis, water thyme, common elodea, and ditch moss.

References

Gallery