Egeria densa
From The Plant Encyclopedia
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| Egeria Densa | |
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Egeria densa | |
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About
Egeria densa (syn. Anacharis densa (Planch.) Vict., Elodea densa (Planch.) Casp.; Large-flowered Waterweed or Brazilian Waterweed) is a species of Egeria native to warm temperate South America in southeastern Brazil, Argentina, and Uruguay.<ref name=grin>Germplasm Resources Information Network: Egeria densa</ref>
It is an aquatic plant growing in water up to 4 m deep, with trailings stems to 2 m or more long, producing roots at intervals along the stem. The leaves are produced in whorls of four to eight, 1–4 cm long and 2–5 mm broad, with an acute apex. It is dioecious, with male and female flowers on separate plants; the flowers are 12–20 mm diameter, with three broad, rounded, white petals, 8–10 mm long on male plants, and 6–7 mm long on female plants.<ref name=fnwe>Flora of NW Europe: Egeria densa</ref><ref name=fna>Flora North America: Egeria densa</ref><ref name=jeps>Jepson Flora: Egeria densa</ref><ref name=wa>Washington Department of Ecology: Egeria densa</ref>
Cultivation and uses
Egeria densa is a popular aquarium plant, but is no longer sold in some areas due to its invasive potential. Plants in cultivation are all a male clone, reproducing vegetatively.<ref name=fna/><ref name=jeps/>
It grows well in the cooler aquarium and is suitable for the beginner. It is easily propagated by cuttings. According to reports (cf. Tropica link) it secretes antibiotic substances which can help prevent blue-green algae. It grows best in a Nutrient rich, high light situation.
Invasive species
E. densa has escaped from cultivation and become naturalized and invasive in many warm temperate to subtropical regions of the world, including Europe, southern Africa, Asia, Australia, New Zealand and North America.<ref name=grin/> In the United States it occurs from New York south to Florida and west to California and Oregon.<ref name=fna/> In the Sacramento-San Joaquin Delta of California, it was introduced in the 1960s and has since had a significant adverse impact on the local ecosystem. The plant currently infests 2,400 ha, or 12% of the total surface area of the delta. It is also a problem in several other states. It has been found in Canada. Most of its impact occurs in the shallow waterways. The plant forms thick mats that obstruct boat passage, clog water intakes and aqueducts, trap sediments, crowd out native vegetation, and impede the migration of anadromous fish.<ref>Foschi, P. G., Fields, G., & Liu, H. (undated). Detecting a Spectrally Variable Subject in Color Infrared Imagery Using Data-Mining and Knowledge-Engine Methods. PRRS04-018. Available online (pdf file)</ref><ref name=capc>California Department of Boating and Waterways: Aquatic Pest Control</ref>
References
External links
- Tropica
- Species Profile- Brazilian Waterweed (Egeria densa), National Invasive Species Information Center, United States National Agricultural Library. Lists general information and resources for Brazilian Waterweed.
