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Care Guide: Elodea

Living Care Information

Elodea, Egeria
Commonly known as waterweed

Quick Start Information

  • Brazilian Elodea is frequently referred to in the classroom and in the aquarium trade as Elodea, but it is properly classified as Egeria densa. In this guide Elodea refers to both Egeria densa and Elodea canadensis.

  • We ship Elodea (Egeria densa) in packs of 12, 25, or 50 plants in plastic bags without water.

  • The plant is also available as Elodea tips in a jar of water.

  • Elodea can vary in color from dark brown to bright green depending on the time of year and conditions at the collection site.

  • We collect our Elodea. Due to this, there may be other organisms present in your shipment.

About the Organism

  • There are Elodea species native to both North and South America.
  • Elodea plants live underwater except when small white flowers bloom at the water’s surface to produce seeds.
  • Elodea’s main reproductive strategy occurs when stalks detach from the parent plant, float away, root and produce new plants.
  • Elodea beds provide an important nursery habitat for aquatic invertebrates and young fish.
  • Brazilian Elodea (Elodea densa) is an invasive species in many parts of the world.
  • Domain: Eukarya
  • Kingdom: Plantae
  • Phylum: Magnoliophyta
  • Class: Liliopsida
  • Order: Hydrocharitales
  • Family: Hydrocharitaceae
  • Genus: Egeria or Elodea
  • Species: densa, canadensis, najas


Elodea can be purchased year-round. Elodea is a freshwater organism and should be kept in dechlorinated tap water. Water from the tap in most municipalities contains chlorine and chloramines which are not removed by off-gassing. Water should be treated with a dechlorinating agent.

Elodea arrives in a sealed plastic bag without water. Upon arrival the bag should be opened, and the Elodea kept moist, or it should be placed directly in the habitat.

Since our Elodea is collected, a range of color can be expected, anywhere from emerald green to brownish, depending on growing conditions at the collection site. As long as the foliage is firm and not shedding excessively it is healthy and ready for use.



If you intend to use Elodea in a laboratory investigation, you can use the plants immediately after rinsing them. For optimum results of your investigations, we recommend transferring them to water and putting them under lights for 2 days before using them. This allows the plants time to recover from any shipping shock.

Shallow containers with a broad surface area are best for holding plants until they are used for the lab. Use either tap water treated to remove chlorine and chloramines or spring water. We do not recommend distilled or deionized water, as these lack minerals needed by the plants. Clip the rubber bands from the stems and spread the plants into a single layer in the water. A fluorescent light bank or a 23- to 32-W compact fluorescent bulb in a desk lamp will provide the intense light needed by the plants. If you must keep the plants for several days before lab use, replace about 1/4 of the water every third day. This is to prevent mineral depletion.


If you plan on using your Elodea as an aquarium specimen, provide the habitat with 10 to 12 hours of light per day at 3 to 5 watts per gallon. Keep the habitat at temperatures ranging from 50 to 77° F for Egeria densa, and 45-65°F for Elodea canadensis. Your container should be large enough to submerge the entirety of the Elodea in treated water. Elodea can grow if it is free floating, but it does grow more vigorously if it is rooted in a substrate.


Depending on the make-up of your aquarium community, it may be necessary to add an aquatic plant fertilizer to replenish depleted mineral content. Iron is of primary concern as Elodea depletes this mineral rapidly. Leaf chlorosis is the most common sign of iron deficiency. Leaves yellowing at the edges only may be showing signs of potassium deficiency.

Aquatic plant fertilizers are available from many aquarium supply or garden shops. Follow the manufacturer’s instructions for adding the fertilizer to your aquarium.

If the aquarium also contains animal inhabitants, phosphate and nitrate levels should also be monitored to ensure the continued health of the aquarium community.

Maintaining and culturing

Specimens of Elodea used for a lab can be propagated in an aquarium as described above.See the Housing (Aquarium) section.


Egeria densa is considered invasive in many parts of the world. Carolina provides living organisms for educational purposes only. As a general policy, we do not advocate the release of organisms into the environment. In some states, it is illegal to release organisms, even indigenous species, without a permit. The intent of these laws is to protect native wildlife and the environment.

Invasive aquatic vegetation is a conservation issue in many areas, therefore, any plants that are no longer needed should be placed in a sealed container and frozen for 72 hours. Dispose of materials according to local and state guidelines.

Please contact your local (state) Department of Agriculture for any specific restrictions on release and disposal of organisms.


No biosafety information applies for this organism.



How can I use Elodea to study photosynthesis?

During photosynthesis, the plant absorbs carbon dioxide from the water and releases oxygen. Since oxygen is much less soluble in water than is carbon dioxide, the water quickly saturates with oxygen and bubbles form. The number of bubbles released per minute measures the rate of photosynthesis. Alternately, use a simple volumeter to measure the increase in volume of gas caused by the release of oxygen.

What is the difference between Elodea and Elodea Tips?

Elodea consists of Elodea sprigs that are about 11 cm (4 ¼") in length. We recommend these for aquarium plants and for studies of photosynthesis, although they can be used also for cell studies. Elodea Tips are the terminal 3 to 4-cm ends cut from sprigs. We recommend these as best for cell studies.

Why can’t you ship me Elodea?

Some states restrict us from shipping Elodea densa because they consider it an invasive plant. We usually substitute Elodea canadensis, a native non-invasive plant, for orders going to restricted states; however, there are times when Elodea canadensis is not available and we must substitute another plant. Never release a non-native plant or animal into your local environment. To discard an aquatic plant, place it in a plastic bag and freeze it for at least 72 hours before discarding the unopened bag in the trash.

Can I substitute other plants for Elodea densa?

For photosynthesis studies, almost any aquatic plant will work. These include Ludwigia, Cabomba, Myriophyllum, Ceratophyllum, and Sagittaria. For easy viewing of plant cells with chloroplasts, consider Fern Prothallia.

Need help?

We want you to have a good experience. Orders and replacements: 800.334.5551, then select Customer Service. Technical support and questions: caresheets@carolina.com