Egeria densa
Encyclopedia
Egeria densa is a species of Egeria
native to warm temperate South America
in southeastern Brazil
, Argentina
, and Uruguay
.
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 flower
s 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.
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 Nutrient rich, high light situation.
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. 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 sediment
s, crowd out native vegetation, and impede the migration
of anadromous fish.
Egeria (genus)
Egeria is a genus of two species of aquatic plants in the family Hydrocharitaceae, native to warm-temperate South America.The genus was formerly included in the related genus Elodea, from which it differs in having the leaves in whorls of four or more, not three, and in having more conspicuous...
native to warm temperate South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
in southeastern Brazil
Brazil
Brazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
, and Uruguay
Uruguay
Uruguay ,officially the Oriental Republic of Uruguay,sometimes the Eastern Republic of Uruguay; ) is a country in the southeastern part of South America. It is home to some 3.5 million people, of whom 1.8 million live in the capital Montevideo and its metropolitan area...
.
It is an aquatic plant
Aquatic plant
Aquatic plants are plants that have adapted to living in aquatic environments. They are also referred to as hydrophytes or aquatic macrophytes. These plants require special adaptations for living submerged in water, or at the water's surface. Aquatic plants can only grow in water or in soil that is...
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
Leaf
A leaf is an organ of a vascular plant, as defined in botanical terms, and in particular in plant morphology. Foliage is a mass noun that refers to leaves as a feature of plants....
are produced in whorls of four to eight, 1–4 cm long and 2–5 mm broad, with an acute apex. It is dioecious
Plant sexuality
Plant sexuality covers the wide variety of sexual reproduction systems found across the plant kingdom. This article describes morphological aspects of sexual reproduction of plants....
, with male and female flower
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
s 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.
Cultivation and uses
Egeria densa is a popular aquariumAquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
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
Aquarium
An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...
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 naturalizedNaturalisation (biology)
In biology, naturalisation is any process by which a non-native organism spreads into the wild and its reproduction is sufficient to maintain its population. Such populations are said to be naturalised....
and invasive in many warm temperate to subtropical regions of the world, including Europe
Europe
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
, southern Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
, Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...
and North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. In the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
it occurs from New York
New York
New York is a state in the Northeastern region of the United States. It is the nation's third most populous state. New York is bordered by New Jersey and Pennsylvania to the south, and by Connecticut, Massachusetts and Vermont to the east...
south to Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and west to California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and Oregon
Oregon
Oregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
. In the Sacramento-San Joaquin Delta
Sacramento River Delta
The Sacramento-San Joaquin River Delta, or California Delta, is an expansive inland river delta and estuary in northern California in the United States. The Delta is formed at the western edge of the Central Valley by the confluence of the Sacramento and San Joaquin rivers and lies just east of...
of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, it was introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
in the 1960s and has since had a significant adverse impact on the local ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
. 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
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. Most of its impact occurs in the shallow waterways. The plant forms thick mats that obstruct boat passage, clog water intakes and aqueducts, trap sediment
Sediment
Sediment is naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself....
s, crowd out native vegetation, and impede the migration
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
of anadromous fish.
External links
- Tropica
- Species Profile- Brazilian Waterweed (Egeria densa), National Invasive Species Information Center, United States National Agricultural LibraryUnited States National Agricultural LibraryThe United States National Agricultural Library is one of the world's largest agricultural research libraries, and serves as a National Library of the United States and as the library of the United States Department of Agriculture...
. Lists general information and resources for Brazilian Waterweed.