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Aquatic Plant ID
They go by different names. You may call them “weeds,” “grass” or “moss.” Aquatic plants are an integral part of the Tennessee River’s ecosystem, whether providing nutrients for the species at the bottom of the food chain, cover and ambush areas for largemouth bass or food source for the multitude of local waterfowl.
This guide provides information to help you understand when these plants are most productive, where they grow and—most importantly—help you identify them. Whether you are an angler, property owner or any other lake user, we invite you to learn more about the aquatic plants present in our Tennessee Valley region reservoirs.
The guide also offers season-by-season tips for fishing among these plants.
Floating and Floating Leaf Plants
Hydrilla
Two types of non-native hydrilla (Hydrilla verticillata), D-hydrilla and M-hydrilla, have different growth habits but will both eventually form dense canopy mats during the summer.
Description
Hydrilla is a bottom-rooted rhizomatous submersed perennial with branching stems that grow to the surface. The leaves are farther apart at the base and closer toward the plant’s top. Lower leaves usually grow in pairs on opposite sides of the stem or in groups of three. Middle and upper leaves grow in whorls of 5 to 7. The leaves are about ¼ inch wide and up to an inch long, with sharp-toothed edges and tiny spines on the underside of the midvein.
Single 1/8-inch wide white or translucent pistillate flowers grow on a thin stalk from the leaf axil near the growing tip. The flowers have three sepals, three petals and three stamens or styles. Hydrilla reproduces by breaking into fragments from turions formed in the leaf axil and from underground tubers produced on the rhizomes.
Two biotypes of invasive hydrilla exist in TVA reservoirs: monoecious (M-hydrilla) and dioecious (D-hydrilla). While the two look similar, their growth habits are very different. D-hydrilla often appears larger and more robust than M-hydrilla. D-hydrilla typically grows upward first, while the M-hydrilla grows into a mat on the bottom first and then turns towards the surface. Both eventually form dense canopy mats during summer.
Habitat
Hydrilla is a non-native plant that has been introduced across the United States. It forms dense mats in still or flowing water up to 20 feet deep and tolerates a broad range of physical and chemical conditions. Because hydrilla can clog waterways, displace native species and can be difficult to control, it can cause severe water use conflicts. Hydrilla primarily occurs in reservoirs in the central portion of the Tennessee Valley region.
Identifying Features
What It Looks Like—Small, pointed leaves whorled around the stem, most often in sets of four to six. Distinguishing the two biotypes from one another can be very difficult, but an apparent size difference (D-hydrilla being larger) can often be seen.
Where to Find It—Hydrilla is one of the most abundant plants in the TVA reservoir system. It is very aggressive and grows out into deep water, making it one of the easiest to find.
Similar Species—This species resembles Canadian elodea and Brazilian elodea. Canadian elodea is often much smaller and whorls are in sets of three or less. Brazilian elodea is often larger and does not produce the characteristic hydrilla tubers.
Seasonal Fishing Techniques
Spring—D-hydrilla will be some of the only plant material to make it through the winter. Finding these mats can provide for some early grass fishing. M-hydrilla, on the other hand, will be sprouting from tubers creating an emerging grass edge early in the spring.
Summer—D-hydrilla typically grows upward first, forming dense canopy mats during summer. But an open understory often exists where big bass can hide. Fish heavy punch baits. If you can get them below the top layer, you should get a bite. M-hydrilla is more difficult to fish in summer. It first covers most of the bottom, then begins growing toward the water's surface. This growth habit often leads to a “wall-like” bed of vegetation with few holes and very little understory for fish to hide in. Flip holes created by underwater obstructions (logs, rocks) or fish the edge of these impenetrable mats.
Fall—Both D-hydrilla and M-hydrilla provide excellent cover for the frog bite of fall. M-hydrilla will begin to die back in middle- to late-fall, leaving open areas beneath floating mats. D-hydrilla will continue to maintain the canopy and understory which are conducive for big bass. As these and other plants decay, a “slime” of algae will begin to form, and fish will take advantage of newly released nutrients. Find the combination of decaying plants and “slime,” and give them all you’ve got.
Winter—D-hydrilla will slow growth and die back but should maintain clumps of vegetation around existing root crowns. This will be some of the only grass available for fishing in winter, so target isolated clumps with a slow presentation. M-hydrilla will die back completely in winter, so little structure is left behind to target.
Drawbacks
Hydrilla is one of the primary plants managed in the TVA system. Growing as much as 2 to 5 inches per stem per day in summer, this plant can quickly impede all recreational activities, including fishing access.
Shoreline Plants
Hydrilla
Two types of non-native hydrilla (Hydrilla verticillata), D-hydrilla and M-hydrilla, have different growth habits but will both eventually form dense canopy mats during the summer.
Description
Hydrilla is a bottom-rooted rhizomatous submersed perennial with branching stems that grow to the surface. The leaves are farther apart at the base and closer toward the plant’s top. Lower leaves usually grow in pairs on opposite sides of the stem or in groups of three. Middle and upper leaves grow in whorls of 5 to 7. The leaves are about ¼ inch wide and up to an inch long, with sharp-toothed edges and tiny spines on the underside of the midvein.
Single 1/8-inch wide white or translucent pistillate flowers grow on a thin stalk from the leaf axil near the growing tip. The flowers have three sepals, three petals and three stamens or styles. Hydrilla reproduces by breaking into fragments from turions formed in the leaf axil and from underground tubers produced on the rhizomes.
Two biotypes of invasive hydrilla exist in TVA reservoirs: monoecious (M-hydrilla) and dioecious (D-hydrilla). While the two look similar, their growth habits are very different. D-hydrilla often appears larger and more robust than M-hydrilla. D-hydrilla typically grows upward first, while the M-hydrilla grows into a mat on the bottom first and then turns towards the surface. Both eventually form dense canopy mats during summer.
Habitat
Hydrilla is a non-native plant that has been introduced across the United States. It forms dense mats in still or flowing water up to 20 feet deep and tolerates a broad range of physical and chemical conditions. Because hydrilla can clog waterways, displace native species and can be difficult to control, it can cause severe water use conflicts. Hydrilla primarily occurs in reservoirs in the central portion of the Tennessee Valley region.
Identifying Features
What It Looks Like—Small, pointed leaves whorled around the stem, most often in sets of four to six. Distinguishing the two biotypes from one another can be very difficult, but an apparent size difference (D-hydrilla being larger) can often be seen.
Where to Find It—Hydrilla is one of the most abundant plants in the TVA reservoir system. It is very aggressive and grows out into deep water, making it one of the easiest to find.
Similar Species—This species resembles Canadian elodea and Brazilian elodea. Canadian elodea is often much smaller and whorls are in sets of three or less. Brazilian elodea is often larger and does not produce the characteristic hydrilla tubers.
Seasonal Fishing Techniques
Spring—D-hydrilla will be some of the only plant material to make it through the winter. Finding these mats can provide for some early grass fishing. M-hydrilla, on the other hand, will be sprouting from tubers creating an emerging grass edge early in the spring.
Summer—D-hydrilla typically grows upward first, forming dense canopy mats during summer. But an open understory often exists where big bass can hide. Fish heavy punch baits. If you can get them below the top layer, you should get a bite. M-hydrilla is more difficult to fish in summer. It first covers most of the bottom, then begins growing toward the water's surface. This growth habit often leads to a “wall-like” bed of vegetation with few holes and very little understory for fish to hide in. Flip holes created by underwater obstructions (logs, rocks) or fish the edge of these impenetrable mats.
Fall—Both D-hydrilla and M-hydrilla provide excellent cover for the frog bite of fall. M-hydrilla will begin to die back in middle- to late-fall, leaving open areas beneath floating mats. D-hydrilla will continue to maintain the canopy and understory which are conducive for big bass. As these and other plants decay, a “slime” of algae will begin to form, and fish will take advantage of newly released nutrients. Find the combination of decaying plants and “slime,” and give them all you’ve got.
Winter—D-hydrilla will slow growth and die back but should maintain clumps of vegetation around existing root crowns. This will be some of the only grass available for fishing in winter, so target isolated clumps with a slow presentation. M-hydrilla will die back completely in winter, so little structure is left behind to target.
Drawbacks
Hydrilla is one of the primary plants managed in the TVA system. Growing as much as 2 to 5 inches per stem per day in summer, this plant can quickly impede all recreational activities, including fishing access.
Submersed Plants
Hydrilla
Two types of non-native hydrilla (Hydrilla verticillata), D-hydrilla and M-hydrilla, have different growth habits but will both eventually form dense canopy mats during the summer.
Description
Hydrilla is a bottom-rooted rhizomatous submersed perennial with branching stems that grow to the surface. The leaves are farther apart at the base and closer toward the plant’s top. Lower leaves usually grow in pairs on opposite sides of the stem or in groups of three. Middle and upper leaves grow in whorls of 5 to 7. The leaves are about ¼ inch wide and up to an inch long, with sharp-toothed edges and tiny spines on the underside of the midvein.
Single 1/8-inch wide white or translucent pistillate flowers grow on a thin stalk from the leaf axil near the growing tip. The flowers have three sepals, three petals and three stamens or styles. Hydrilla reproduces by breaking into fragments from turions formed in the leaf axil and from underground tubers produced on the rhizomes.
Two biotypes of invasive hydrilla exist in TVA reservoirs: monoecious (M-hydrilla) and dioecious (D-hydrilla). While the two look similar, their growth habits are very different. D-hydrilla often appears larger and more robust than M-hydrilla. D-hydrilla typically grows upward first, while the M-hydrilla grows into a mat on the bottom first and then turns towards the surface. Both eventually form dense canopy mats during summer.
Habitat
Hydrilla is a non-native plant that has been introduced across the United States. It forms dense mats in still or flowing water up to 20 feet deep and tolerates a broad range of physical and chemical conditions. Because hydrilla can clog waterways, displace native species and can be difficult to control, it can cause severe water use conflicts. Hydrilla primarily occurs in reservoirs in the central portion of the Tennessee Valley region.
Identifying Features
What It Looks Like—Small, pointed leaves whorled around the stem, most often in sets of four to six. Distinguishing the two biotypes from one another can be very difficult, but an apparent size difference (D-hydrilla being larger) can often be seen.
Where to Find It—Hydrilla is one of the most abundant plants in the TVA reservoir system. It is very aggressive and grows out into deep water, making it one of the easiest to find.
Similar Species—This species resembles Canadian elodea and Brazilian elodea. Canadian elodea is often much smaller and whorls are in sets of three or less. Brazilian elodea is often larger and does not produce the characteristic hydrilla tubers.
Seasonal Fishing Techniques
Spring—D-hydrilla will be some of the only plant material to make it through the winter. Finding these mats can provide for some early grass fishing. M-hydrilla, on the other hand, will be sprouting from tubers creating an emerging grass edge early in the spring.
Summer—D-hydrilla typically grows upward first, forming dense canopy mats during summer. But an open understory often exists where big bass can hide. Fish heavy punch baits. If you can get them below the top layer, you should get a bite. M-hydrilla is more difficult to fish in summer. It first covers most of the bottom, then begins growing toward the water's surface. This growth habit often leads to a “wall-like” bed of vegetation with few holes and very little understory for fish to hide in. Flip holes created by underwater obstructions (logs, rocks) or fish the edge of these impenetrable mats.
Fall—Both D-hydrilla and M-hydrilla provide excellent cover for the frog bite of fall. M-hydrilla will begin to die back in middle- to late-fall, leaving open areas beneath floating mats. D-hydrilla will continue to maintain the canopy and understory which are conducive for big bass. As these and other plants decay, a “slime” of algae will begin to form, and fish will take advantage of newly released nutrients. Find the combination of decaying plants and “slime,” and give them all you’ve got.
Winter—D-hydrilla will slow growth and die back but should maintain clumps of vegetation around existing root crowns. This will be some of the only grass available for fishing in winter, so target isolated clumps with a slow presentation. M-hydrilla will die back completely in winter, so little structure is left behind to target.
Drawbacks
Hydrilla is one of the primary plants managed in the TVA system. Growing as much as 2 to 5 inches per stem per day in summer, this plant can quickly impede all recreational activities, including fishing access.