Egeria densa

Taxobox
name = "Egeria densa"

---

image_width = 240px
image_caption = Egeria Densa
regnum = Plantae
divisio = Magnoliophyta
classis = Liliopsida
ordo = Alismatales
familia = Hydrocharitaceae
genus = "Egeria"
species = "E. densa"
binomial = "Egeria densa"
binomial_authority = Planch.

"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.Germplasm Resources Information Network: [http://www.ars-grin.gov/cgi-bin/npgs/html/taxon.pl?400175 "Egeria densa"] ]

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.Flora of NW Europe: [http://ip30.eti.uva.nl/BIS/flora.php?selected=beschrijving&menuentry=soorten&id=4167 "Egeria densa"] ] Flora North America: [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=220004601 "Egeria densa"] ] Jepson Flora: [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?Egeria+densa "Egeria densa"] ] Washington Department of Ecology: [http://www.ecy.wa.gov/programs/wq/plants/weeds/aqua002.html "Egeria densa"] ]

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.

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 nutriment rich, high light situation.

As an invasive species

"Egeria 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. In the United States it occurs from New York south to Florida and west to California and Oregon. 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. 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.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 [http://www.public.asu.edu/~huanliu/papers/prrs04.pdf online (pdf file)] ] California Department of Boating and Waterways: [http://www.dbw.ca.gov/aquatic.asp Aquatic Pest Control] ]

References

External links

* [http://www.tropica.dk/productcard_1.asp?id=058 Tropica]