Garden Ecology - Publications

Common Reed
Phragmites australis

The Common Reed . . . VERY common. Ecologists and natural resource managers are quite concerned about the spread of this of this water loving invasive plant. We chose some east end locations where the plant is well established to illustrate what makes it tick and what it tells us about the surrounding environment.

Do you recognize this tall reed? You’ve probably seen it!

It looks similar to some ornamental grasses that are a popular garden plant. Common Reed, or Phragmite (frag-my-’tee) as is often called, has a wide leaf blade that can get over 2 feet long. Mature stands can have plants that reach up to 12 feet tall! The previous year’s cane often remains into the next growing season as does the fluffy seed head.

This plant can also be identified by it distictive rhizome. Rhizomes are type of root that grows horizontally just below the surface of the soil. New top growth and roots grow out of the rhizome as the plant moves across the landscape. Rhizomes are important to Common Reed’s success because they are hollow and allow for the efficient exchange of air and nutrients. Air is limited in poor wet soils, yet oxygen is a critical element in the kinds of soils that allow good plant growth. This is why Phragmite is such a tough competitor in poor soils and challenging wetland conditions.

Pull up a reed by the root and you’ll see the creamy yellow colored root. Sometimes you can find a rhizome spreading on the soil surface sending out shoots and roots every 6-8” or so. By growing in this fashion it does not have to seeds to propagate. Instead, mature plants can spawn new plants and from a distance provide the young shoots with the nutrients they need until they establish themselves in the new location. These tools make Phragmite very effective at colonizing disturbed ground, such as old construction sites, especially where water quality and drainage patterns are disturbed. A strong stand of Phragmites is usually a good indication that the land has been compromised in some fashion.

Unfortunately Common Reed has a reasonable tolerance to salt. Brackish wetlands are subject to colonization. Stands are frequently found in coastal waterfront sites where fresh and salt water meet. We visited Northwest Harbor in East Hampton where plants can be seen advancing from the upper marsh where the water has less salt to lower marsh ares where the salt content increases. Along with the loss of native habitats, the economic impact of Common Reed is huge. Dense reed stands grow so tall they easily block waterfront
views, seriously decreasing property value.

One place that Phragmites can frequently be found invading is salt
marshes that are predominantly made up of grass species from the
genus Spartina. These are the low grasses that you see in the front of this photo, with the Phragmites behind. Salt marshes are productive areas that provide a multitude of benefits to the environment, including helping to filter water, providing nutrition for a number of animals, and serving as a habitat for many commercially important species, all services which Phragmites may not necessarily provide. They are extremely important areas to protect!

Here we are at the storm water drainage ditch outflow near Haven’s
beach in Sag Harbor. Rain water that falls upland of this beach front,
including runoff from fertilized lawns, streets and side walks makes its way into this ditch. Ground water coming from the dense residential community serviced by conventional leaching pool septic systems also seeps into the ditch and out into the bay. This questionable water is untreated and enters the bay right next to Sag Harbor’s only public swimming beach. This is a picture perfect habitat for the invasive Phragmite.

Upland of Haven’s beach, this road side drain takes all of the water that runs off the road during a storm and channels it underground to the ditch.

The Peconic Estuary program is working to reduce this problem by creating catchbasins and containment tanks which would help trap contaminated sediment before they enter the marine environment.

The day we were filming at Haven’s beach, we saw children playing in water coming out of the ditch. This water is polluted and beyond the obvious health threat to humans, the Peconic Estuary System is greatly stressed by having to deal with the effects caused by contaminated water.

Phragmites seem to flurish in eutrophic wetlands areas such as this one. There is little competition in these conditions since most native plants are not well adapted to high nutrient, anoxic soils.

Other environmental threats: Once established Common Reed creates very low light conditions at the soil level which excludes native grasses and perennials from growing. The rigid dense reeds can prevent many important native animals from moving in and out of wetland sites. For example, some turtle species require constant and easy access to wetlands for food and cover, a barrier of reeds can keep them exposed and vulnerable.

This dense stand is growing along the Haven’s Beach drainage ditch.

In pre-colonial days what is now Sag Harbor’s waterfront would have been nearly all tidal wetlands with about 50% saltmarsh. Areas like Haven’s Beach where filled overtime. Now most of the fringe wetland marshes are channelized into ditches where water and soil quality is poor. And, you guessed it, there are is Phragmite growing.

Phragmites can be controlled and healthy wetlands restored but this is typically a job for restoration experts and extensive permitting is always required. Selectively cutting of Common Reed and removing the waist is surprisingly simple and effective method of control. Cutting is done two time a year and many sites see substantial benefits in two -three years.

By learning how to identify invasive plants like Common Reed, and by understanding what the presence of an invasive tells us about the environment, both past and present, we are taking an important step in the active stewartship of our landscape.

If you have Phragmite growing on your property and wouldn like more information on controlling it, please feel free to contact us.