The importance of aquatic ecosystems

Aquatic plants are essential to a lake ecosystem like trees are to a forest. They provide many ecosystem services that not only benefit humans, but also native fish, waterfowl, and invertebrates. Aquatic plants are the “primary producer” of lakes. They turn nutrients from water and soil into plant matter eaten by all types of aquatic wildlife. These herbivores are then consumed by larger fish in the lake. Plants are the foundation to aquatic food webs. Additionally, they provide shelter for many species of native fish including northern pike and yellow perch.

Healthy lakes need aquatic plants

Clean, healthy lakes are dependent upon aquatic plants. They absorb phosphorus and produce dissolved oxygen that fish and other aquatic life depend on for survival. Plant root systems stabilize sediment both within and around lakes, reducing shoreline erosion and keeping the lakes clear. Our Yahara lakes attract many visitors each year and serve as a social, economic, and cultural epicenter for the people of the watershed.

Learn about aquatic plant management in the Yahara lakes.

Below is a brief survey of the 24 aquatic plant species the Dane County Land & Water Resources Department found in their 2017 study of the Yahara lakes of Greater Madison.

Coontail

Scientific name: Ceratophyllum demersum
Other names: hornwort
Stems: pale green, hollow, glabrous
Leaves: 1-4 cm., dark green, 5-14 whorled leaves, glabrous
Flowers: <2mm, translucent, late summer
Ecology: Coontail is eaten by waterfowl, turtles, snails, and carp. It also provides hiding places for many small organisms. It is a nuisance because it can be transported to other bodies of water by clinging to boats and occasionally aggregates along shorelines.

Muskgrass

Scientific name: Chara spp.
Other names: stonewort
Stems: Pale green, no more than three cells thick, glabrous
Leaves: 2 cm., gray-green, 6-16 whorled branchlets, glabrous
Flowers: none
Ecology: Muskgrass is a genus of macro-algae that closely resembles an aquatic plant. It gets its name from the garlic-like odor it produces. Ducks feed on muskgrass and small fish use it for habitat as it grows on muddy lake bottoms. It can also be called stonewort because the algae is covered in a lime deposit that is gritty to the touch.

Common waterweed

Scientific name: Elodea canadensis
Other names: elodea, American elodea, common elodea, anacharis, Canada waterweed
Stems: dark green, branched, glabrous
Leaves: 5-13 mm., dark green, 2-3 whorled leaves, glabrous
Flowers: white, 3-4 petals, summer
Ecology: Except for the flowers, this common waterweed grows entirely underwater. It provides both food and habitat for wildlife, and the flowers help beautify the surrounding environment. Additionally, it is a great source of oxygen for lake ecosystems.

Water star-grass

Scientific name: Heteranthera dubia
Other names: grassleaf mudplantain
Stems: slender, pale green, branching, glabrous
Leaves: 15 cm., dark green, simple, alternate, slender, glabrous
Flowers: 2 cm., yellow, 6 narrow tepals, summer
Ecology: Though consumed by waterfowl, water star-grass is not an important food source. It provides habitat to some small organisms, but is more enjoyed by tourists than anyone else. This is the only plant on the survey that grows in the surrounding wetland and not the actual lake.

Small duckweed

Scientific name: Lemna minor
Other names: lesser duckweed, common duckweed
Stems: none
Leaves: 2-5 mm., medium green, 1-2 round leaves
Flowers: 2 mm., white/yellow petals, single, spring-summer
Ecology: This plant consists of a single floating thallus (vegetative structure that is both the leaf and the stem), with a short root like structure. It reproduces mostly by budding, in which is creates a clone of itself. Insects, ducks, and turtles feed upon it. Small duckweed can form large colonies, and can deplete lakes of oxygen by shading out the underwater photosynthesizers.

Northern watermilfoil

Scientific name: Myriophyllum sibiricum
Other names: shortspike milfoil
Stems: pale green/pink, branched, hollow,
Leaves: 1-5 cm., medium green, 5-14 leaflet pairs, whorled, feathery, glabrous
Flowers: 1 cm., red, 4-parted, summer
Ecology: The flowers of this plant are used by pollinators, and several native fish and waterfowl species use the leaves for food and habitat.

Eurasian watermilfoil (Invasive)

Scientific name: Myriophyllum spicatum
Other names: spiked watermilfoil
Stems: pinkish, glabrous, up tp 20 ft. long
Leaves: 12-21 whorled leaflets, limp, green, glabrous
Flowers: 3mm., pink, late summer-early fall
Ecology: This is an invasive species. It is rooted in the lake bottom and grows to the surface of the lake to form thick mats. Very few animals feed on it, the most effective biocontrol is a beetle called the watermilfoil weevil. It can spread by breaking off into segments and attaching to boats. Eurasian watermilfoil can now be found in 45 states. Read more about Eurasian watermilfoil.

Bushy pondweed

Scientific name: Najas flexilis
Other names: bushy naiad, water naiad, brittle naiad, slender naiad, spiny leaf naiad
Stems:  2 ft., pale green, slender, branching, glabrous
Leaves: slender, sub-opposite, toothed margins, 2.5 cm., dark green, glabrous
Flowers: small, white
Ecology: Waterfowl consume the entire plant, and it is also used by many native fish (bass, pike, etc.) for cover.

American lotus

Scientific name: Nelumbo lutea
Other names: duck acorn, water nut
Stems: none
Leaves: single, 1-2.5 ft., orbicular and concave, wavy margin, dark green, glabrous
Flowers: 10-20 cm, 10-20 petals, white/pale yellow, mid- to late summer
Ecology: These plants have root-like rhizomes submerged in the water, and vegetation grows entirely above the water. American lotus is a great source of pollen for bees and other pollinators. Their acorn-like seeds are also consumed by many waterfowl.

White water lily

Scientific name: Nymphaea odorata
Other names: fragrant water lily, lily pad
Stems: none
Leaves: 10-30 cm. Wide, orbicular, medium green, leathery, glabrous
Flowers: 10-20 cm, white, 20-30 petals, yellow stamen, summer-early fall
Ecology: Lily pads provide cover for many native fish species, along with pollen for insects. Mammals, such as muskrats and beavers, prefer these plants as a food source. Even deer sometimes enter shallow lakes to feed on these lilies. Due to the beautiful flower, they are often planted in residential ponds. The leaves of this plant grow directly from the rootstock, meaning there are no stems.

Leafy pondweed

Scientific name: Potamogeton foliosus
Other names: pondweed
Stems: pale green, slender, flexible, glabrous
Leaves: 6 cm., olive green, linear, tapering, glabrous
Flowers: 2 mm., greenish-brown, clustered together, summer
Ecology: The complex structure of leafy pondweed provides habitat to a variety of aquatic wildlife. The leaves are also sometimes eaten by fish, small mammals, and waterfowl. The root system is a large source of food for beetle larvae.

Long-leaf pondweed

Scientific name: Potamogeton nodosus
Other names: long-leaved pondweed
Stems: 2-8 ft., pale greenish-yellow, glabrous
Leaves: 3-15 cm., light to medium green, tapering, glabrous
Flowers: 3 mm., greenish-brown, emergent on spikes, late summer
Ecology: The seeds, roots, and leaves of long-leaf pondweed are consumed by fish, insects, and waterfowl. Several species of moths use material from this plant to form their cocoon.

Curly-leaf pondweed (Invasive)

Scientific name: Potamogeton crispus
Other names: curled pondweed
Stems: 3 ft., light yellowish-green, flattened, glabrous
Leaves: 5-15 cm., olive green, stiff, wavy, glabrous
Flowers: 4-6 mm., greenish-red, 4 petals, late spring-early summer
Ecology: This is an invasive species from Europe found in the Yahara Lakes. It mostly reproduces from vegetative burs, that spread clones of the plants. It can grow well in muddy or disturbed waters and can dominate entire sections of the lake. Because it is able to grow in cold waters, curly-leaf pondweed is often one of the first aquatic plants to emerge in the early spring.

Fries’ pondweed

Scientific name: Potamogeton friesii
Other names: flat-stalked pondweed
Stems: 1 ft., light green, flattened, glabrous
Leaves: 4 cm., dark green, slender, alternate, glabrous
Flowers: 3 mm., greenish-brown, summer
Ecology: Fries’ pondweed has a high tolerance for eutrophication, and often thrives in disturbed habitats. It can be used as shelter for some young fish, and its leaves can be consumed by waterfowl.

Variable pondweed

Scientific name: Potamogeton gramineus
Other names: grass-leaved pondweed
Stems: 20 cm., pale green, branched, glabrous
Leaves: 15 cm., reddish-green, alternate, tipped, glabrous
Flowers: 4 mm., greenish-brown, located on emerged spike, summer
Ecology: Variable pondweed gets its name because it has seven different hybrids. The submerged part of this plant is an important food source for various native fish and waterfowl. Invertebrates use the emerged part of the plant as nesting areas.

Illinois pondweed

Scientific name: Potamogeton illinoensis
Other names: shining pondweed
Stems: pale green, red spots, branched, glabrous
Leaves: 4-20 cm., red-green, tapered, spiraling, pale stipule, leathery when above water
Flowers: 7 cm., green-yellow, 8-15 whorles,
Ecology: The submerged leaves of this plant are thinner and flatter, therefore making them an important food source for waterfowl and some native fish. Illinois pondweed also forms loose colonies, but these are seldom a nuisance.

Clasping-leaf pondweed

Scientific name: Potamogeton richardsonii
Other names: Richardson’s pondweed
Stems: pale green, branched, glabrous
Leaves: 16-130 cm., dark green, alternate, glabrous
Flowers: small, white, 4 petals
Ecology: Clasping-leaf pondweed provides submerged habitat for aquatic insects.

Flat-stem pondweed

Scientific name: Potamogeton zosteriformes
Other names: narrow-leaf pondweed
Stems: dark green, flattened, branched, glabrous
Leaves: 3 cm., light green, alternate, stiff, entirely submerged, glabrous
Flowers: small, green-brown, emerge from water
Ecology: Flat-stem pondweed is one of the most common species found in midwestern lakes, and it can survive in almost all water depths.

Wild celery

Scientific name: Vallisneria americana
Other names: water celery, eelgrass, tapegrass
Stems: light green, coiled, horizontal, glabrous
Leaves: 7 ft., various shades of green, ribbon-like, translucent, glabrous
Flowers: 3 cm., white, 6 petals
Ecology: The stems of wild celery grow horizontally underwater, and the long ribbon-like leaves can grow up to 7 feet and emerge from the water. The leaves of this plant provides shade to native fish (bluegills, perch, etc.), along with waterfowl and shorebirds.

Common watermeal

Scientific name: Wolfia columbiana
Other names: water lentil
Stems: none
Leaves: 1-1.5 mm., pale green, globe-shaped, glabrous
Flowers: very small, white
Ecology: Common watermeal is the smallest flowering plant on Earth. It is made up of just a globe (not a true leaf) and has no stems or roots. Despite being native, it grows in large colonies and is often mistaken for algae. While these colonies provide food for birds and fish, they often shade out larger submerged plants.

Horned pondweed

Scientific name: Zannichellia palustris
Other names: horned poolmat
Stems: light green, filiform, glabrous
Leaves: 2.5-7.5 cm., medium green, linear, opposite, tapering, flattened, glabrous
Flowers: no petals, only ovary visible
Ecology: This is one of the most common aquatic plant species in the world, and can be found on every continent except Antarctica. The foliage and fruit of the horned pondweed are consumed by insects and waterfowl. The foliage also provides habitat for fish and insect species.

Large duckweed

Scientific name: Spirodela polyrhiza
Other names: giant duckweed
Stems: no stem
Leaves: 3-9 mm., dark green, glossy
Flowers: very tiny, no petals, occasional, can bloom year-round
Ecology:This plant consists of a single floating thallus (vegetative structure that is both the leaf and the stem), with a short root like structure. It reproduces mostly by budding, in which is creates a clone of itself. Insects, ducks, and turtles feed upon it. Large duckweed can form large colonies, and can deplete lakes of oxygen by shading out the underwater photosynthesizers.

Sago pondweed

Scientific name: Stuckenia pectinata
Other names: comb pondweed
Stems: 1-3 ft., light green, flattened, glabrous
Leaves: 4-13 cm., olive green, tapering, alternate, glabrous
Flowers: 1-3 cm., green-brown, clumped on whorls, late spring-early fall
Ecology: Sago pondweed is one of the most important food sources for waterfowl because their roots contain edible tubers, which are nutritionally valuable. Muskrats and many different types of turtles feed on the foliage of this plant.

Common bladderwort

Scientific name: Utricularia vulgaris
Other names: great bladderwort
Stems: 20 cm., pale green, rootlike, glabrous
Leaves: 4 cm., pale green, finely divided, covered in “bladder”, glabrous
Flowers: 2 cm., yellow, 2-lipped, fragrant, summer
Ecology: The common bladderwort floats on the surface of a lake with the stems and leaves slightly submerged. The leaves contain small sac-like “bladders” that trap and digest small invertebrates when they swim by. They are also consumed by various fish and waterfowl.

Yahara lakes surveys

Dane County and the Wisconsin Department of Natural Resources (DNR) did a plant survey of the Yahara Lakes in 2017 and published these results in their 2017 Aquatic Plant Management Plan. Read about our Yahara lakes:

• Mendota
• Monona
• Waubesa
• Kegonsa
• Wingra

Thank you Paul Skawinski!

Thank you to Paul Skawinski for sharing his aquatic plant photos with Clean Lakes Alliance! Learn more about aquatic plants in his book: Aquatic Plants of the Upper Midwest. The book is available for purchase from the Extension Lakes Bookstore.

Additional useful links

• Aquatic plant management in the Yahara lakes
• http://www.illinoiswildflowers.info/
• https://www.dnr.state.mn.us/nr/plants/aquatic/index.html
• https://aquaplant.tamu.edu/plant-identification/
• http://wisflora.herbarium.wisc.edu/index.php

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