Throughout history, scientists have debated how to classify plants and animals. The classification system of biomes was developed by scientist Victor Shelford. Shelford's system defines broad biotic units of plants and the animals that are associated with them. Freshwater biomes are further classified into two broad types: lentic and lotic. The difference is defined by water flow. Lotic systems include streams and rivers where water flows. Lentic systems are still waters such as ponds and lakes.
Phytoplankton thrive in open water. In open water of deeper water bodies, photosynthesis occurs within these organisms. Sunlight, a necessary ingredient for photosynthesis, cannot penetrate deep into the water.
Algae are one type of non-vascular plant associated with freshwater biomes. Non-vascular plants do not have a system of roots and stems to distribute water within the plant. Plants such as algae rely on their water environment to serve this purpose.
Duckweed is a floating aquatic plant. While found in both lotic and lentic systems, duckweed is more likely to occur in still waters. It is an important food source for waterfowl and provides habitat for micro-invertebrates.
Arrowhead or duck potato is a perennial, emergent plant found in the shallow waters of freshwater biomes. Emergent plants are rooted underwater, with stems and leaves that will emerge above the water surface. Arrowhead is an important wildlife plant. Waterfowl, beavers and muskrat will feed on the nutritious tubers
Water lilies, with their familiar heart-shaped leaves, are common, emergent plants. They can form dense colonies, providing habitat for macro-invertebrates and fish. Deer, beaver and other animals will eat the leaves and roots and shoots of water lilies.
There are over 100 species of sedges. Sedges can be distinguished from grasses by their triangular stems. They can form thick tussocks, providing habitat for aquatic organisms. The entire plant provides food for wildlife, including its seeds, which are consumed by waterfowl and songbirds.
Cattails are identified by their characteristic cigar-shaped flowers called catkins. They are found in shallow shoreline areas. Roots and shoots provide food for muskrats and waterfowl. Cattails are typically found in lentic and slower-moving lotic systems.
Bulrushes are found in moist soils along shorelines of freshwater biomes. Some species such as the giant bulrush, can grow quite tall, reaching up to 10 feet. They are perennial plants that can form dense colonies along shorelines.
The common reed is often associated with cattails. It can be an aggressive and invasive plant, establishing colonies as freshwater biome waters recede with seasonal changes.