Why are those floating plants in your pond? – Tallahassee.com

One of the great things about living in Leon County is the mild, relaxing climate that allows us to enjoy all seasons. Our enjoyable climate also means that many different species of plant life thrive in our area. For those of us that live on or near a pond or lake, we may wonder about the plant life growing along the edges, rooted on the bottom, or floating on the surface.

The presence of these floating plant species is part of a healthy, natural process. However, if they become too abundant, they can have a negative impact on the ecosystem and take away from the beauty of open water. When this happens, an intervention may be necessary to prevent a disturbance in the ecosystem from happening.

The most common floating plants that can be found in Leon County waterbodies are duckweed (Lemna spp.), mosquito fern (Azolla filiculoides), water spangle (Salvinia minima), water lettuce (Pistia stratioites), and water hyacinth (Eichhornia crassipes). Duckweed and mosquito fern are native to Leon County, but the previous species are considered invasive and exotic, and are capable of out-competing native plants and disrupting the natural processes of our unique Florida ecosystems.

So, how can you tell the different plant species apart? Duckweed, for example, (which is often used to name any small, floating plant) has leaves that are less than ¼ inches long and thin hair-like roots. As its name implies, ducks are quite fond of this plant and can eat a small pond’s worth in a few weeks.

Mosquito fern has small leaves that overlap each other. Each plant is between one and two inches across and often appears red in color. Mosquito fern will seldom take over ponds and lakes, but can be found mixed in with other floating species.

Water spangles can be found in most bodies of water and in some cases, can take over a small pond. Water spangle leaves are oval-shaped and are covered by many small, stiff hairs. The leaves can be about ¼ to ½ inches wide, with each clump of leaves being about two inches across.

Water lettuce is a larger plant and, as its common name implies, it looks like lettuce floating on the water’s surface. The leaves are at least two to three inches long. It is usually a light green color with no flowers. This plant can quickly take over a small pond.

The water hyacinth is larger than the previous plants described above. It has dark green leaves with obvious veins that run parallel to each other. The stalk of the leaf is often expanded and spongy. The flowers are quite beautiful. Unfortunately, this is one of our most invasive and exotic aquatic species.

The floating plants most likely to cause concern are water spangles, water lettuce, and water hyacinth. Control can be accomplished through manual removal, herbicide sprays, and/or water level manipulations. Each one of these methods has pros and cons that should be considered, in addition to a combination of methods that are most successful.

The staff at the Leon County Extension Office is eager to help with questions regarding the identification and control of these species. For more information, contact Leon County Public Works at 606-1500 or the Leon County Extension Office at 606-5200.

Mark Tancig is a Water Resource Specialist with the Leon County Public Works Department. For gardening questions, email us at Ask-A Mastergardener@leoncountyfl.gov.

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