Elodea canadensis | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Monocots |
Order: | Alismatales |
Family: | Hydrocharitaceae |
Genus: | Elodea |
Species: | E. canadensis |
Binomial name | |
Elodea canadensis | |
Synonyms | |
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Elodea canadensis (American waterweed or Canadian waterweed or pondweed) is a perennial aquatic plant, or submergent macrophyte, native to most of North America. [1] [2] [3] It has been introduced widely to regions outside its native range and was first recorded from the British Isles in about 1836. [4]
The native range of the species lies within North America, but it has been introduced in many parts of the world either intentionally or not. Europe has been particularly affected with the first record dating back as far as 1836. [5] Since then, the species' presence has been confirmed in all continental European countries. [6]
Records of the species' presence in Ireland include: County Galway, found at several sites along the Eglinton Canal, County Galway, [7] County Down. and from the Lagan Canal near Lisburn, Northern Ireland. [8]
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, translucent, oblong, 6–17 mm long and 1–4 mm broad, borne in whorls of three (rarely two or four) round the stem. [9] 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.These stalks, or hypanthia, are the lower part of the petals joined to form a floral tube. This floral tube can be up to 30 centimeters (12 inches) in length, while only 1/25 inch (one millimeter) in width. [10] for a length to length to width ratio of 300. However, according to one article, this ratio can sometimes be as much as one thousand, [11] making this species, by a wide margin, "the skinniest of all flowers".
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, spindle-shaped and smooth. It flowers from May to October. [1] [2] [3] [12]
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 light levels. [12]
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. Egeria densa is also a larger, bushier plant, with longer leaves. [13]
It is frequently used as an aquarium plant. Propagation is by cuttings. [14]
It is an invasive species in Europe, Asia, Africa, and Oceania. 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. [15] [12] [13] [16]
Other common names for this plant include Anacharis (an older name for the genus Elodea), water thyme, common elodea, and ditch moss.[ citation needed ]
Hydrocharitaceae is a flowering plant family including 16 known genera with a total of ca 135 known species, that including a number of species of aquatic plant, for instance the tape-grasses, the well known Canadian waterweed, and frogbit.
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 vegetation and laboratory demonstrations of cellular activities. It lives in fresh water. An older name for this genus is Anacharis, which serves as a common name in North America.
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 Asia, Africa and Australia, with a sparse, scattered distribution; in Australia from Northern Territory, Queensland, and New South Wales.
Egeria is a genus of three species of aquatic plants in the family Hydrocharitaceae described as a genus in 1849. native to warm-temperate South America.
Cornus canadensis is a species of flowering plant in the dogwood family Cornaceae, native to eastern Asia and North America. Common names include Canadian dwarf cornel, Canadian bunchberry, quatre-temps, crackerberry, and creeping dogwood. Unlike its relatives, which are for the most part substantial trees and shrubs, C. canadensis is a creeping, rhizomatous perennial growing to about 20 centimetres tall.
Egeria densa, the large-flowered waterweed or Brazilian waterweed, is a species of Egeria native to warm temperate South America in southeastern Brazil, Argentina, Chile and Uruguay. It is considered a problematic invasive species due to its use in home aquariums and subsequent release into non-native ecosystems.
Elodea nuttallii is a species of waterweed 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.
Veronica serpyllifolia, the thyme-leaved speedwell or thymeleaf speedwell, is a perennial flowering plant in the plantain family. It is native to Europe, but can be found elsewhere on most continents as an introduced species.
Myriophyllum verticillatum, the whorl-leaf watermilfoil or whorled water-milfoil, is a native to much of North America, North Africa, and Eurasia. It closely resembles another native milfoil, called northern water milfoil Whorled water milfoil is also easily confused with four types of invasive milfoils: Eurasian water milfoil, Variable water-milfoil, Parrot feather, and hybrid water milfoil.
Nitella flexilis, the smooth stonewort, is a freshwater species of characean algae that is used as a model organism for its large cell size and relative ease of cultivation in the laboratory.
Potamogeton gramineus is a species of aquatic plant known by the common name various-leaved pondweed, variableleaf pondweed, grass-leaved pondweed or grassy pondweed, native to the northern hemisphere where it grows in shallow, clean water.
Potamogeton compressus is a species of aquatic plant known by the common names grass-wrack pondweed, flatstem pondweed and eel-grass pondweed.
Lagarosiphon major is a monocotic aquatic plant native to Southern Africa. Common names include African elodea, curly waterweed, oxygen weed and South African oxygen weed. It is used as freshwater aquarium plant.
In botany, a whorl or verticil is a whorled arrangement of leaves, sepals, petals, stamens, or carpels that radiate from a single point and surround or wrap around the stem or stalk. A leaf whorl consists of at least three elements; a pair of opposite leaves is not called a whorl.
Decodon verticillatus, the sole species in the genus Decodon, is a flowering plant in the family Lythraceae. It is commonly known as waterwillow or swamp loosestrife. It is native to wetlands in the eastern half of the United States and Canada.
Podostemum ceratophyllum, commonly known as the hornleaf riverweed, is a species of submerged aquatic plant in the family Podostemaceae. It is native to eastern North America where it grows on hard bottoms in swiftly flowing rivers and streams and is considered a foundation species.
Oenanthe fluviatilis, the river water-dropwort, is a flowering plant in the carrot family, Apiaceae, which is endemic to north-west Europe. It grows only in clear, unpolluted rivers and is declining throughout its range.