Anacharis Facts, Care & Planting (Elodea densa)

Anacharis is similar in appearance to other oxygenating aquatic plants like hornwort (Ceratophyllum demersum) and waterthymes (Hydrilla verticillata), however they tend to appear less bushy than their counterparts. Their thin 1 to 4 cm (0.4-1.5 in) leaves form rings or whorls that extend up the length of delicate stems attached to a single root base. These plants appear anywhere from bright green to dark, seaweed-like green in color. Anacharis is a favorite learning tool of science teachers across the globe. The needle-like leaves of anacharis are only one to two cells thick and are an ideal way to introduce students to the plant cell structure, with the chloroplasts and cell walls easily seen under simple microscopes.

Anacharis has many names including Brazilian elodea, egeria, Brazilian waterweed, common waterweed, dense waterweed, and leafy elodea. One of the reasons anacharis has many names may be because of the number of places it has cropped up across the globe. Originally from eastern South America, anacharis has spread from its native areas in Brazil, Uruguay, and Argentina to all continents except Antarctica.

This plant is more than just a pest, though. Anacharis is valued for its ability to take up water pollutants and inhibit the growth of harmful bacteria by limiting the nutrients in the water and releasing antibacterial chemicals. A recent study found that the addition of anacharis to a widely used wastewater treatment model increased the effectiveness of the system, which uses certain types of bacteria to decontaminate water, and lead to a significant decrease in the production unwanted chemical byproducts. Another research group in Malaysia found that anacharis could be used to remove arsenic and zinc from wastewater produced by gold mining.

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Anacharis Growth, Hardiness & Wintering

Anacharis grows rapidly and have been known to reach heights of 3m (10ft) in the wild. Thick growths of anacharis look like masses of submerged pine branches because their stalks grow both upward and sloped along the water’s surface. Anacharis produces a tri-petal white flower with a yellow center about 12-20 mm (less than 0.75 in) in diameter. These flowers bloom in the summer, but little information has been recorded on their blooming duration. Similarities with other plants in their family, however, suggest each flower is likely short-lived.

Anacharis can survive in water temperatures from 15 to 30° C (59 to 86° F), and prefers a neutral pH range of 6.5 to 7.5. Anacharis is a forgiving plant and tolerates a wide range of conditions but does best with moderate sunlight. Anacharis can survive the freezing of surface water, but will not survive in prolonged subzero temperatures. To contextualize the survivability of this plant, one study by the Michigan Department of Agriculture found that anacharis had the potential to establish wild populations over 77.8 percent of the total area of the United States.

How to Plant Anacharis:

If you are able to choose your plant, avoid yellowing, browning, or dark green specimens as their color change indicates they have undergone some form of stress already and may fail to flourish in their new habitat. Additionally, any ties use to bind bunches of plants should be removed immediately—even if not planting right away, to avoid damage to the delicate stems. The ends of the stems may need a 1 to 2cm (less than 0.5 in) trimming if they appear dry, cracked, or damaged.

The easiest way to grow anacharis is to drop them onto the surface of your pond or aquarium. Alternatively, anacharis can survive planting depths up to 4m (13ft). To plant underwater, remove the bottom 2.5cm (1in) of leaves and tuck the plant into the bottom sediment. You should anchor the plants in 2.5-5cm (1-2in) of substrate to prevent them from surfacing. You could also plant them as described in pots and then submerge the pots for faster removal or easier pruning, although this may lead to the roots rotting overtime. Anacharis is not picky in terms of planting medium and can handle just about whatever is currently sitting in the bottom, including aquatic soil, loam, and even aquarium gravel. Individual anacharis plants should be spaced a minimum of 2.5cm (1in) apart to help prevent direct nutrient competition.

Anacharis should be watched closely to make sure it does not dominate your pond or aquarium. Regular pruning or pulling of entire plants is suggested, especially if you do not own critters like painted turtles or goldfish to keep the growth in check.

As with other fast growing aquatic plants, overwintering may be more effort than it is worth. However, if you are in an area where your pond may freeze beyond surface ice formation, trim several stems at least 20cm (8in) in length. These clippings can be kept indoors floating or submerged in a tub or aquarium with moderate light (2 watts per gallon for aquariums).

Is Anacharis Toxic, Poisonous or Invasive?

Anacharis is considered illegal or subject to government regulation in a number of states in the U.S. For this reason, you should always check with your local government before purchasing a plant online—especially one as fast growing as anacharis. In 2017, the plant was one of several popular aquarium plants to be banned by the European Union for its invasive potential.

Anacharis is illegal in the following states  –  AL, CT, ID, IL, IN, LA, MA, ME, MI, MS, MT, NE, NH, NY, OH, OR, SC, VT, WA, WI.

Anacharis is believed to be one of the only aquatic plants to establish itself in the Arctic. Wild populations of anacharis have been found in the warmer geothermal waters of northern Iceland since 2013, and springs in southern Iceland since 2003. This is especially concerning given that this jump is over 1000km (about 700mi) from its previously identified extreme habitat range. The finding of invasive aquatic plants in the Arctic is an indicator that anacharis can survive nearly anywhere in the world. Gardeners and aquarium owners should be especially careful when discarding unwanted plants or clippings to safeguard their local waterways.

Will Koi, Goldfish, & Pond Fish Eat Anacharis?

Goldfish love eating elodea plants, anacharis included. Since anacharis is particularly inexpensive and easy to find in most pet stores, it makes an excellent addition to the habitat of these voracious eaters.

Most other fish use anacharis as shelter, although some gardeners have noticed that their gouramis (Osphronemidae family), tetras (Characidae family) and swordtails (Xiphophorus helleri) may snack on them as well. Slider (Trachemys spp.) and Painted (Chrysemys picta) turtles love anacharis, and some pet owners have reported their turtles shredding the anacharis in their tanks at an astonishing rate.