Brazilian elodea
(Egeria densa)
Biological Category
Plants
NY Legal Status
N/A
Species Type
Aquatic Invasives
DESCRIPTION
Egeria densa is a dioecious, submersed perennial found in lentic and lotic freshwater systems. Only male plants are found in the U.S. and in its native range male plants outnumber female plants by as much as 6:1.
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Leaves: Serrated and linear leaves seen in whorls of four to eight along the stem; small white flowers with 3 petals, bloom in late spring and in fall; 3 or more leaves per node along the stem
Introduced world-wide through the aquarium trade – sold widely as good “oxygenator” plant and dispersed secondarily by boat trailers and vegetative dispersal downstream.
This species may be transported by hitchhiking on recreational gear; E. densa grows in thick mats that can become entangled on boat propellers and trailer wheels, or can be captured in bilge water. Attached fragments can be transported between water bodies.
Egeria densa is an aquatic plant in the waterweed family that inhabits mild to warm freshwaters, such as slow flowing streams of warm, temperate, and tropical regions. It occurs at depths as deep as 7 m. It grows in thick mats of intertwining stems, which alter the light and nutrients available to the biota where it occurs, acting as an ecosystem engineer.
Flowers float above the water surface and are pollinated by insects. It reproduces asexually in Australia and in the U.S. where only the male plant has established. Egeria densa is capable of vegetative fragmentation; stems of at least two nodes can break off from the parent colony and disperse by stream flow. Stem fragments that break off can take root in bottom mud or grow as free-floating mats. Fragmentation can occur as a result of the mechanical shearing of water flows, wave action, waterfowl activity, and boating.
Brazilian elodea forms dense mats in waterways and reduce habitat for fish, recreational value, and outcompetes native plants for sunlight; it has been seen to cause large losses to the hydroelectric companies. These plants form in dense stands and restrict water movement, trap sediment and create fluctuations of water quality. With the instability of water movement, these plants can cause interruptions of electricity generation and damage to grids and equipment. The large stands of these plants also lower recreational value of waterways and interfere with navigation, fishing, swimming and water skiing.
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