Coontail
(Ceratophyllum spp.)
Description
Coontail, also known as “Hornwort,” is a dark green, submerged perennial aquatic plant. It lacks true roots but can be loosely anchored to the bottom by specialized, finely divided stems called rhizoids. The plant’s fan-shaped leaves are relatively stiff and are arranged in whorls of five or more. These leaves have many forks and small teeth along the edge or midrib, giving the plant a rough texture. Coontail can grow long and sparse, reaching lengths of over 4.6 meters (15 feet), but often appears bushy near the tips, resembling a raccoon’s tail or a Christmas tree. Unlike water milfoil (Myriophyllum spp.) or fanwort (Cabomba caroliniana), Coontail leaves are spiny and forked rather than featherlike. The flowers are very small and rarely seen. Reproduction occurs by seed or vegetative growth of plant fragments, with tiny flowers located at the leaf base on very short stalks that remain submerged. Pollination occurs underwater, and the plant produces small, hard, oval seeds with three spines.
Distribution
Coontail is native to the entire United States and most of Canada and is found in many countries worldwide. It thrives in freshwater to slightly brackish waterways and prefers high nutrient levels. This plant species is also sold as an ornamental for aquariums and ponds.
Habitat
Coontail can float on the water surface and form dense colonies covering large areas. It grows best in calm waters of lakes, ponds, marshes, and streams, at depths up to 6 meters (20 feet). The plant can grow in high-nutrient waters and tolerates shade more than most submerged aquatic plants. Coontail remains green and continues to grow throughout the winter.
Impacts to the Aquatic Ecosystem
Coontail provides valuable habitat for young fish such as bluegill, perch, and largemouth bass, as well as small aquatic insects. Some fish and waterfowl consume its shoots and seeds. However, Coontail can develop dense subsurface mats in high nutrient waters, displacing or out-competing other native vegetation. These dense mats can deplete oxygen levels, impede recreational activities, and create mosquito habitats. Despite these issues, Coontail helps improve water quality by absorbing nutrients from the water.
Prevention and Control
Mechanical Control
Coontail can be harvested by cutting, raking, or mowing. It is crucial to remove and destroy stem fragments, as the plant can reproduce from these fragments. Mechanical harvest methods, such as suction dredging, have shown effectiveness. Bottom barriers that cover and shade the infested areas can also smother Coontail. These barriers include polyvinyl chloride sheets, small mesh screens, and natural fibers, best installed in the spring before the plants produce significant biomass.
Biological Control
Triploid sterile Grass Carp (White Amur) are non-native herbivorous fish that can consume Coontail, but they will first eat other preferred aquatic plants. These fish are strictly controlled and may be purchased only from approved hatcheries after obtaining the appropriate state permit.
Chemical Control
Contact herbicides such as diquat, endothall, and various chelated copper products can treat Coontail but may have short-lived results. Systemic herbicides containing 2,4-D and fluridone are also effective, as they are absorbed into the plant. These herbicides can take longer to act and are best applied in water bodies with minimal to no water exchange. Proper identification, timing, and regulatory compliance are crucial for effective chemical control.
