Species and Varieties

Water plants are a natural part of every pond ecosystem. They serve many purposes and are a valuable food source. On this page, find Penn State Extension’s resources on identifying the various types of aquatic plants and algae. In addition, discover advice on planktonic algae and invasive species control.

Types of Aquatic Plants

Aquatic plants are highly beneficial to pond inhabitants. Identifying and understanding the various types of water plants is vital for learning how to manage them. Most aquatic plants are categorized as either submerged, emergent, or floating.

Submerged plants are rooted at the bottom of the pond and grow up through the water column. They grow best in shallower water that allows sunlight to reach the bottom. Popular submerged aquatic plants include elodea and naiad.

Emergent plants are typically found on the pond’s banks and shallow areas. Many of them offer benefits such as helping control erosion along with bank areas and limiting sediment runoff into the water. Cattails and bur-reed are two of the more common emergent plants.

Floating plants float on the water surface and prefer growing in still water. Species, such as duckweed and watermeal, can grow to resemble a thick carpet covering the pond and serve as a food source for waterfowl. Another well-known floating plant is the water lily. Water lily has large leaves and is an ideal habitat for fish and aquatic insects.

Invasive Aquatic Plants

Invasive water plants are often species that out-compete the native aquatic plants. Purple loosestrife is a common invasive species in Pennsylvania. This emergent plant has a showy, purple flower and may cause significant damage by choking out waterways. Other concerning species include hydrilla and European water chestnut.

Using invasive plants in your pond or water garden should be avoided under most circumstances. When choosing a water plant, it is best to select species that are either native to your region or are non-invasive exotic plants. Further information is available in the PA and Mid-Atlantic guide to water species, as well as the free aquatic invasives webinar.

Common Types of Algae

Algae serves as food sources for aquatic life and is an essential part of any pond ecology. In ponds, algae can present itself either as microscopic planktonic algae or as a leafy plant. Planktonic algae causes the water to appear green or brown and often appears suddenly, under favorable nutrient and sunlight conditions. It is considered beneficial and is at the base of the food chain in ponds and lakes.

Filamentous algae is another variety commonly found in Pennsylvania ponds. This dark green plant forms thick mats and gas bubbles. It’s important to note that during the summer months, filamentous algae may reach nuisance levels. Excessive growth may cause damage, as well. This can lead to concerns such as swimming nuisance, interference with fishing, and fish kills.

Nitella and Chara are other common types of algae. Nitella prefers growing in acidic ponds with soft sediments, while Chara prefects more alkaline, hard water ponds. Both varieties are considered valuable and can grow abundantly under optimum conditions. Excessive growth, however, should be promptly managed by reducing or redirecting nutrient sources from the pond.

In this section, discover comprehensive information on identifying and managing different types of algae and aquatic plants. Information on controlling water plants and invasives through biological, physical, and chemical means can be found, as well.