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weeds that grow near water

Floating plants

In recent years a growing problem has been posed by a number of introduced aquatic or bog plants. These can be very invasive and can have seriously detrimental effects on gardens and the wider landscape. Species currently banned from sale are:

Aquatic weeds (or pond weeds) can normally be tolerated in small numbers, but it is when they make excessive growth that they become a nuisance, particularly in summer. In garden ponds control is relatively easy, but in larger ponds and lakes it is more difficult.

It is very important that weeds removed from ponds or lakes are composted, buried or burnt. On no account should they be transferred to rivers, other ponds or lakes. Several introduced pond weeds, widely available from garden centres, cause enormous problems where they escape or are introduced into the wild.

Free-floating plants:

Marginals

Alternanthera philoxeroides (alligator weed)
Azolla filiculoides (fairy fern)
Cabomba caroliniana (Carolina fanwort)
Crassula helmsii (New Zealand pygmy weed)
Eichhornia crassipes (water hyacinth)
Elodea nuttallii (Nuttall’s waterweed)
Gunnera tinctoria (Chilean rhubarb)
Hydrocotyle ranunculoides (floating pennywort)
Lagarosiphon major (curly waterweed)
Ludwigia grandiflora (water primrose)
Ludwigia peploides (creeping water primrose)
Lysichiton americanus (American skunk cabbage)
Myriophyllum aquaticum (parrot’s feather)
Myriophyllum heterophyllum (broadleaf watermilfoil)

Invasive water weeds are troublesome in various ways:

What are aquatic weeds?

Submerged plants (aka ‘oxygenators’)

All ponds, from small shallow ponds, to larger lakes can become choked with weeds especially where there is nutrient rich run-off from surrounding agricultural land.

Weeds that grow near water

Once established in a pond, floating pond plants such as duckweed or watermeal can grow extremely quickly making the pond look very unpleasant. Duckweed can overtake a pond and completely cover the surface robbing the pond of light and oxygen.

Also known as Phragmites , is an invasive plant that grows and spreads rapidly. It forms large, dense colonies that can overtake mist areas like ditches and shorelines and out-compete native plant species. Common reed are found in moist soil, up to water 3′ deep and grows up to 15 feet tall with a feathery seed-head that forms later in the summer.

For more information on how to control and remove some of these plants see our pages on Large Pond Weed Control, Large Pond Algae Control and Large Pond Muck & Sludge.

Floating-Leaf Pondweed is common in ponds or slow flowing habitats. It produces mainly floating leaves but also has submersed on the same plant as well. The floating leaves are oblong, pointed at the tips, slightly heart-shaped at the base and grow 5 to 10 cm long, and rounded at the base.

Duckweed

Native to North America, Elodea has small bright green leaves that grow on branching stems. It begins growing very early in the spring in cool water and can be invasive in certain conditions.

Tape Grass (Eelgrass, Wild Celery) grows in shallow water and has long narrow leaves that grow from a cluster at the base of the plant. the leaves grow up to 1 meter long and are only about one centimeter wide. Tape Grass starts growing actively when the water temperature warms up in in the summer months and will divide by sending out runners from the base.

Emergent / Shoreline plants are one of the most common problem in ponds. Cattails, bullrushes, grasses, irises and phragmites can quickly become established in ponds with shallow shorelines in depths of up to 2 feet. Often, these plants initially colonise new ponds by seeds carried by wind, birds or other animals. Once established, many marginal plants can spread rapidly underground making them difficult to control.

Water Plantain

Curly-leaf pondweed is an species that was introduced from Eurasia. It is fast growing plant and can grow very quickly, overtaking other pond plants.

If you are looking for assistance with your pond, we offer Pond Maintenance Services and products specifically for large ponds.

Weeds that grow near water

Image Credit: Pixabay

Duckweed is considered the smallest flowering plant in existence. It flourishes in pond settings and has small, flat leaves and tiny flowers that tend to attract flies, which can be harmful to ponds and annoying for pond owners.

Water lilies are beautiful weeds but they are weeds nonetheless. These plants root into the soil on the bottom of ponds and stretch up to grow on the surface of the water. They rarely take over entire pond ecosystems but should be thinned occasionally to ensure proper sun and oxygen exposure.

This weed can be easily confused with clasping-leaf pondweed. The difference is that curly-leaf pondweed has rounded leaves with small ridges along the edges instead of smooth, blunt leaves. Flowers usually bloom above the water level during the summer months.

16. Southern Naiad

Image Credit: Pixabay

Image Credit: Lenyarts, Shutterstock

Image Credit: Liz Albro Photography, Shutterstock

4. Duckweed

This wild plant helps purify water and can be used to weave items such as storage bowls and wall artwork. Bulrushes look similar to cattails, but they tend to grow in deeper water and can grow in the middle of a pond, whereas cattails only grow around the perimeter in shallow water.

Although beautiful, purple loosestrife is a perennial plant that invades wetlands and ponds throughout most of North America. It grows impressive purple flowers that stand tall above their stalks. Unfortunately, they are known for quickly overtaking other plant life growing in the same environment.