Also known as anarcharis, Brazilian elodea strongly resembles native waterweed. But the plant actually falls into the invasive, non-native category, because the plant hails from Brazil. The plant remains popular in aquariums but presents challenges for people who find it taking over their ponds, lakes and water gardens.
The first specimens of Brazilian elodea appeared in Millneck, Long Island, in 1893. By 1915, elodea was sold for use in aquariums to improve oxygen levels. The first wild elodea specimens showed up in Europe in 1910 in a canal in Leipzig, Germany. Now the invasive plant thrives in Europe, New Zealand, Japan and Chile in addition to the United States.
A freshwater perennial herb, Brazilian elodea looks like a much larger version of waterweed (Elodea canadensis). Sporting bright green leaves that grow to about an inch in length, elodea forms roots in the bottom of ponds and lakes, and continues growing upward until it reaches the water's surface. The plant then spreads to form dense mats. The plant features bright white, 1-inch flowers with three petals that float on the water's surface. The plants start to die back in late summer if hot sunny days prevail, completely dying back in the fall before reappearing in the spring once water temperatures warm up.
Brazilian elodea grows in almost any kind of still or moving water, including lakes, ponds, streams, pools and ditches. It also grows in water gardens, where some gardeners like to use it until they see its invasive tendency. In its native range of Brazil and coastal areas of Argentina and Uruguay, the plant primarily grows in slow-moving, shallow waters.
Most pet shops sell Brazilian elodea or anacharis for use in aquariums, where the plant grows into dense stands perfect for that environment. But a few states prohibit the sale of the plant, including Washington state, because the plant grows so quickly in lakes and ponds once it's accidentally introduced.
One way to stop elodea from spreading requires rinsing all mud and debris from equipment and wading gear before leaving a launch area. Water needs to be drained from boats, too, with an inspection to remove all plant material from the propeller, boat and trailer. Water and plants from aquariums also require proper disposal rather than releasing them into the wild. Gardeners and aquarium users also need to consider using native plants instead of elodea.