Freshwater ecosystems include lakes, rivers, ponds, and streams; they all have low salt concentration. Ponds and lakes can vary in size and have limited plant and animal species. Rivers and streams originate in headwaters; you can see different specie as you move from the headwaters to the mouth of the river; light and oxygen are the determining factors. Wetlands are standing water like marshes and swamps; they have a large variety of plant and specie, including reptiles, amphibians, and birds.

American lotus
American lotus, Center for Aquatic and Invasive Plants, University of Florida, Photos and a 2-3 minute video.
Blue-green Algae
Blue-green Algae, Florida Department of Environmental Protection, A photo and description.
Buttonbush
Buttonbush, Aquaplant @ Texas A&M University, Photo and description.
Carnivorous Plants / Insectivorous Plants
Carnivorous Plants / Insectivorous Plants, Botanical Society of America, A gallery of photos; click on a photo for more photos and information
Carnivorous Plants vs Herbivorous Insects
Carnivorous Plants vs Herbivorous Insects, YouTube.com, Video length: 01:54.
Common Duckweed
Common Duckweed, AcquaPlant, Texas AgriLife Extension Service, Photo and description.
Coontail
Coontail, Center for Aquatic and Invasive Plants, University of Florida, Text, photos, and a 2-3 minute video.
Cypress Trees
Cypress Trees, University of Southern Indiana, Photos and description; check out those "knees".
Diatoms
Diatoms, Kids.Net.Au, Encyclopedic article for younger students.
Diatoms: Life History and Ecology
Diatoms: Life History and Ecology, University of California Museum of Paleontology, Text and two images; click to enlarge.
EEK! Eurasian Water-milfoil
Eurasian Water-milfoil, EEK!m Wisconsin Department of Natural Resources, Information for younger students.
Everglades Habitat Images
Everglades Habitat Images, National Park Service, Visit the web site for the photos.
Flowering Plants that Grow on Bogs and Fens
Flowering Plants that Grow on Bogs and Fens, By Andy Fyon, Ontario Wild Flower, Close-up photos with descriptions.
Macrophytes
Macrophytes, Biology-Online.org, Mostly text with an illustration showing examples of macrophytes.
Nelumbo lutea, the American Lotus
Nelumbo lutea, the American Lotus, Wikipedia.com, Article with photos; click to enlarge.
Plant Identification
Plant Identification, Aquaplant, Texas AgriLife Extension Service, Department of Wildlife & Fisheries Sciences, Texas A&M University, Here you can identify aquatic plants using alphabetical or
Sherpa Guides: The Okefenokee Swamp Flora and Fauna
Sherpa Guides: The Okefenokee Swamp Flora and Fauna, By Richard J. Lenz, Photos with descriptions.
The Charms of Duckweed
The Charms of Duckweed, by John W. Cross, Missouri Botanical Garden, A combination of text, illustration, and photos.
The Value of Riparian Vegetation
The Value of Riparian Vegetation, King County, State of Washington, Text and one photo.
Water Lily Pictures and Lily Pad Pictures
Water Lily Pictures and Lily Pad Pictures BetterPhoto.com Visit the site for photos.
What Are The Common Plants, Animals, And Insects In A Swamp?
What Are The Common Plants, Animals, And Insects In A Swamp?, Michigan Environmental Education Curriculum, Wetland Ecosystems, Visit the web site to view the photos.
Willow
Willow, Aquaplant @ Texas A&M University, Photo and description.