Aquatic Vegetation Identification
Non-native plants in North Carolina waters are responsible for most aquatic weed problems in our state. The lack of natural controls and predators allows these plant species to flourish in public and private waterways. Weeds, (such as hydrilla water hyacinth), impair the water flow of streams and rivers, they clog intakes provide breeding grounds for mosquitoes and other pests. Unwelcome aquatic vegetation can negatively impact the health and appearance of our ponds and lakes and interfere with recreation, displace native species,and they may upset the balance of fish populations.
Pond Lake management can help develop a control or elimination plan to eliminate harmful vegetation from your pond or lake. In the section below you will find a few of the invasive aquatic weed species found In North Carolina. If you find any of these weeds in your pond or lake, give us a call today we can help return your waterway to a healthy environment with an appealing appearance.
Alligatorweed is an aggressive emergent perennial from South America. Stems reach a length of 3 feet or more. Leaves are opposite, entire, and up to 4 inches long. It is distinguished by its small, white, clover-like flowers. Alligatorweed spreads rapidly by fragmentation.
Egeria is a branched submersed perennial from South America. Leaves occur in whorls of 3-6 around a long stem and are up to 1 inch long and 1/5 inch wide with finely toothed margins. Flowers are about 1/2 inch in diameter, white, and 3 petaled. Similar in appearance to hydrilla but is usually distinguished by its smooth texture and larger leaves and flowers. It is sometimes sold as “Anacharis.”
Phragmites is a perennial grass that reaches 10 feet in height. Leaves are two-ranked, flat, long-attenuate up to 1 1/2 feet long and 1/2 inch wide, blue-green in color with rough margins. The leafy stem is topped by a 1 foot long silvery brown silky panicle of flowers. Common reed reproduces and spreads readily by rhizomes.
This introduced species is a submersed perennial with distinct feathery leaves arranged in whorls of 4 around a long slender stem. Leaves are up to 1 inch long and usually dark green but often with a reddish tint. The flowering stem is very slender and up to 6 inches long with whorls of inconspicuous flowers. Eurasian watermilfoil reproduces by fragmentation.
Giant Salvinia is a small, free-floating, introduced aquatic fern. It usually appears as branched stems with floating leaves in whorls of 3. Floating leaves are light to medium green, suborbicular, and 1/2 to 1 inch long and wide. The upper surface is covered with dense, stiff white hairs with distinct “egg beater” shaped tips.
Hydrilla is an introduced submersed perennial. Leaves are up to 2/3 inch long with sharply toothed margins and occur in whorls of 3-8 around a long thin stem. Sharp teeth located on the lower midrib of the leaves give the plant a rough feel. Hydrilla exhibits multiple branching at a single node. Translucent white flowers are less than 1/4
inch in diameter. It is sometimes sold as “Anacharis.”
Hygrophila is a prolific exotic originally from the East Indies. It is mostly submersed, but a small portion of the plant may extend above the water surface. Leaves are opposite, elliptic to oblong, entire, and 1 1/2 inch long and 1/2 inch wide. Stems are square and grow up to 6 feet. Flowers are white to bluish-white and located in the axils of upper leaves.
Limnophila is a perennial from Southeast Asia. Most of the plant is submersed, but a few inches of the stem and leaves can be emergent. Submersed leaves are up to 1 inch long, feathery, and in whorls about the stem, while emersed leaves are generally lance-shaped with irregular margins. Stems are up to 12 feet long. Single blue to lavender
flowers occasionally occurs on the emersed portion of the stem.
Purple loosestrife is an emergent perennial originally from Europe that grows to 6 feet with multiple woody stalks. Leaves are typically opposite, lance-shaped, and 3 to 4 inches long. It is distinguished by its long dense spike of bright pink/purple flowers at the top of the stems. Each plant can produce millions of seeds annually.
Slender naiad is a submersed annual from Europe that grows to 4 feet in length. Leaves are opposite, very narrow with 7-15 marginal teeth and up to 1 1/2 inches long. The abundant stiff recurved leaves near the end of the branches give the plant a bushy appearance. Inconspicuous flowers and fruit are located in the leaf axils.
Water chestnut is an emersed or floating plant. The lower leaves are submersed, sessile, alternate, and cleft. The upper floating leaves are diamond-shaped with distinct teeth along the leaf margins. The flower of water chestnut has 4 white petals with 4 green sepals. The fruit is nut enclosed in a thorny calyx with 4 sharp spines.
This free-floating plant from Brazil reaches up to 3 feet in height. Leaves are thick, leathery, and elliptic to ovate in shape and emerge from the plant base. The leaf stem is inflated and spongy to provide floatation. The flowering spike contains 5-20 very showy light purple flowers with a yellow spot. Roots are dark, fibrous, and feathery in appearance. This is a very popular water garden plant.
Water lettuce is a free-floating, stoloniferous perennial from the tropical/subtropical regions of the world. Leaves are formed in rosettes, are densely pubescent, grayish to light green in color and up to 6 inches long. Leaf shape is ovate to obovate with a truncate apex. It reproduces vegetatively by forming new plants on stolons.
Water primrose is an emergent perennial that grows to 3 feet tall but
stems may be many feet long when floating on the water. Leaves are
alternate and variable in shape from suborbicular in early growth stages
to lanceolate in the mature stage. Flowers are bright yellow and about
1 inch in diameter with 5-6 sepals.
- NC Cooperative Extension – Aquatic Weeds – https://chatham.ces.ncsu.edu/aquatic-weeds
- Aquatic Nuisance Species Program – SC Department of Natural Resources
- North Carolina State University Libraries