Most tall reeds you see along shorelines, ditches, and marshes are common reed, a giant grass that grows wherever its roots stay wet. The same plant comes in a native North American form and an invasive form from Europe and Asia, and at a glance the two look alike. Whether a reed bed is a problem depends on which one you have. Much of what people value about reed, from roofing to sewage cleaning, comes from the very traits that make the invasive form so hard to stop.
What Common Reed Looks Like
Its scientific name is Phragmites australis (often just called Phragmites), and the invasive form can grow over 15 feet tall.1NYIS. Common Reed – NYIS It grows in dense stands where living stems mix with last year’s standing dead stems.2NYIS. Common Reed – NYIS
The stems are hollow, green with yellow joints in summer and straw-yellow in winter.3NYIS. Common Reed – NYIS Leaves are blue-green to yellow-green, up to 20 inches long and 1 to 1.5 inches wide.4NYIS. Common Reed – NYIS They tend to sit along one side of the stem.5NYIS. Common Reed – NYIS In late summer the plant carries large, feathery, purplish-to-tan seed heads that stay on through winter.
Reed grows best in shallow water about 4 inches deep or less, and less well as water deepens.6PubMed Central. Optimum water supplement strategy to restore reed wetland in the Yellow River Delta Its seeds sprout best in fresh or slightly salty water and almost fail at seawater-like salt levels.7CLEAN – Soil, Air, Water. Effects of Salinity and Water Depth on Germination of Phragmites australis in Coastal Wetland of the Yellow River Delta
Several other plants get called water reeds. Cattails have flat, sword-like leaves and a brown, sausage-shaped head rather than a feathery plume. Reed canarygrass is shorter, with flat leaves and a tighter seed head. Giant reed (Arundo) has thicker stems and grows in drier southern sites. Bulrushes have round, leafless stems.
Native Reed or Invasive Reed
- Leaf sheaths: dead stems of the invasive form keep their papery leaf sheaths, while native stems drop them.
- Stem base color: native stems turn reddish-brown at the base, while invasive stems stay tan-yellow.
- Leaf collar: the collar where leaf meets stem is taller in the native form.
- Stem spots: round dark fungal spots on stems are typical of the native form.8Invasive Plant Science and Management. Morphological traits for rapid and simple separation of native and introduced common reed (Phragmites australis)
- Leaf and husk length: leaf length combined with seed husk length also separates them.9Invasive Plant Science and Management. Morphological traits for rapid and simple separation of native and introduced common reed (Phragmites australis)
A third, Gulf Coast type also exists in the southern US, which can make these traits harder to read.10Wetlands. A rapid method for identifying the origin of North American Phragmites populations using RFLP analysis When traits are mixed, a DNA test can confirm which type you have.11Wetlands. A rapid method for identifying the origin of North American Phragmites populations using RFLP analysis12Botany. Identification of native and invasive subspecies of common reed (Phragmites australis) in Alberta, Canada, by RNase-H-dependent PCR State invasive programs or extension offices can often arrange identification.
To check your own stand, look at several stems rather than one, since single stems vary. Check dead winter stems for clinging sheaths, and peel a leaf back to see the collar. Photograph stem bases and collars so you can send them to an expert.
Any single trait can mislead, because stem color shifts with sun, age, and season. If sheaths cling, stem bases are tan-yellow, and the collar is short, you can be fairly confident it is the invasive form. If traits disagree, treat the stand as unidentified and hold off on removal until an expert weighs in.
It’s worth the care, because native reed matters. It grows in mixed, less dense stands and supports native insects and birds. Removing it by mistake harms habitat and may break rules. Native and invasive reed can also grow side by side, so one patch may need different handling from the next.
Why Invasive Reed Is a Problem
Invasive reed forms stands where it is almost the only plant.13Invasive Species Centre. Invasive Phragmites – Profile and Resources Native plants get crowded out, and plant and animal variety drops.14Invasive Species Centre. Invasive Phragmites – Profile and Resources The rigid, tough stalks stop wildlife from moving through or nesting.15Invasive Species Centre. Invasive Phragmites – Profile and Resources Across Great Lakes wetlands, invasion generally cut both the number of species and their abundance, and it favored generalist species.16Journal of Great Lakes Research. Effects of Phragmites australis invasion and management on Great Lakes coastal wetland fauna: A taxon-based review It also changes fish and wildlife habitat and the way water flows through wetlands.17U.S. Geological Survey Fact Sheet. Invasive Phragmites in the Great Lakes Wetlands
Sedges, wildflowers, and smaller grasses lose light because reed shades the ground beneath its dense canopy. Animals that eat or nest in those plants lose their food and cover along with them. Thick litter from old stems builds up and keeps seeds of other plants from reaching bare soil.
At a lakefront property, lake views and water access disappear behind a wall of stems, and shoreline paths and docks get swallowed. Dry winter stands can be a fire risk.
A patch also doesn’t stay put. Underground stems creep outward each year, broken stem pieces can root downstream, and seeds blow to new wet ground. Small new patches are far easier to stop than established ones.
How to Control Invasive Reed
Reed stores food in underground stems that resprout after the top is cut. So any method has to drain those underground reserves, which is why a single mowing accomplishes so little.
One approach is cutting stems below the water surface, which starves the roots of air. This cut underground growth by up to 99% in high water.18USGS. Phragmites management in high water: Cutting plants under water limits biomass production, carbohydrate storage, and rhizome viability Cutting every 2 to 3 weeks over two growing seasons worked best, cutting root reserves 75 to 92%.19Journal of Great Lakes Research. Multi-year cut-to-drown management limits Phragmites australis growth, belowground resources, and rhizome viability in Great Lakes wetlands Less frequent cutting may give similar results, though.20Journal of Great Lakes Research. Multi-year cut-to-drown management limits Phragmites australis growth, belowground resources, and rhizome viability in Great Lakes wetlands The method fits stands standing in water, not dry ground.
The other main approach is herbicide. Glyphosate gave 82% control and imazapyr 93% the next spring after summer or fall spraying.21Invasive Plant Science and Management. Common Reed (Phragmites australis) Response to Postemergence Herbicides In fall the plant pulls sugars, and herbicide with them, down into its roots.22PubMed Central. Invasive Phragmites australis management outcomes and native plant recovery are context dependent That makes fall the standard window, though summer spraying of glyphosate also worked.23Invasive Plant Science and Management. Common Reed (Phragmites australis) Response to Postemergence Herbicides Use products labeled for water use and follow local permits.
Follow-through matters as much as the first treatment. Several years of herbicide greatly reduced reed and increased native plants around Chesapeake Bay.24Ecosphere. Landscape and site factors drive invasive Phragmites management and native plant recovery across Chesapeake Bay wetlands Treated sites still did not fully match untouched marshes, and results varied widely from site to site.25Ecosphere. Landscape and site factors drive invasive Phragmites management and native plant recovery across Chesapeake Bay wetlands A moth that bores into stems cut stem mass by up to 64% and is being tested as a future biocontrol.26Biological Control. Impact of Archanara geminipuncta (Lepidoptera: Noctuidae) on aboveground biomass production of Phragmites australis
A realistic year looks like this: spray or cut in late summer to fall, then cut and remove the dead stems over winter once treatment has done its work. Next spring and summer, spot-treat whatever resprouts. Expect to repeat this for three or more years.
Some mistakes undo the effort. Mowing a dry stand once just thickens the regrowth. Burning alone leaves the roots alive. Digging spreads pieces of underground stem that can resprout. And stopping after one good year lets the reed rebound.
Small patches you can reach on foot can be treated stem by stem, while large stands usually need broader spraying. Whichever method you pick, first confirm the reed is the invasive form.
Large stands or water bodies often need licensed applicators, and permits are commonly required in wetlands. Neighbor cooperation helps too, since a patch next door can reinvade a cleared shoreline.
Is Herbicide Safe for Fish and Wildlife
Water-approved diquat, glyphosate, and imazapyr usually had negligible or short-lived effects on fish and water invertebrates.27Environmental Reviews. Aquatic herbicide applications for the control of aquatic plants in Canada: effects to nontarget aquatic organisms Fish survived equally in sprayed and unsprayed wetland areas when glyphosate was used at normal rates.28PubMed. Environmental fate and non-target impact of glyphosate-based herbicide (Roundup) in a subtropical wetland Some added surfactants can be more toxic than the herbicide itself, though.29Environmental Reviews. Aquatic herbicide applications for the control of aquatic plants in Canada: effects to nontarget aquatic organisms Diquat badly damaged nearby native plants even at 6% of label rate, and it killed small freshwater shrimp-like animals below label rate.30PubMed Central. Effects of the Aquatic Herbicide Diquat on Non-Target Aquatic Biota: A Mesocosm Study So pick water-labeled products without harsh additives, and avoid diquat for reed.
To reduce harm, spray the reed only, not open water, and choose calm, dry days. Read the label for aquatic approval, and leave buffer zones near sensitive plants. These findings concern products used as labeled for water, and short-lived effects mean animals may be affected briefly and then recover.
What Reeds Are Good For
Reed beds calm waves, and their roots hold shorelines, even in winter.31Limnology and Oceanography. Under which conditions can tidal reeds contribute to shore protection? The critical interplay between external stress and internal stress resistance in brackish marshes This helps most on gently sloping, soft shores where waves are the main cause of erosion. Where erosion is severe, invasive reed’s dense roots may still help hold soil.32Long Island Invasive Species Management Area. Common Reed (Phragmites australis) – Long Island Invasive Species Management Area
Coastal reed beds in the Baltic held on average 17.4 kg of carbon per square meter, similar to salt marshes and mangroves.33Estuaries and Coasts. Blue Carbon in Coastal Phragmites Wetlands Along the Southern Baltic Sea Most of that carbon sits in mud and roots, not stems.34Biogeosciences. Carbon storage in coastal reed ecosystems Draining or digging up a reed bed can release some of it. Reed beds also hold back rainwater and slow runoff, easing flash floods.35Stonbury. Harnessing the power of nature – Stonbury
Planted reed beds treat sewage for small communities.36Mires and Peat. The utilisation of reed (Phragmites australis): a review Final-stage reed beds typically remove about 10.7 mg/l of nitrogen.37Water Science and Technology. The advantages of a constructed reed bed based strategy for small sewage treatment works
Reed was used for centuries as summer livestock feed and as winter-cut roofing and craft material.38Mires and Peat. The utilisation of reed (Phragmites australis): a review Thatching has an international market.39Ecological Engineering. Commercial viability of paludiculture: A comparison of harvesting reeds for biogas production, direct combustion, and thatching Pressed reed board is light, fire-resistant, breathable, and rot-resistant.40Fens for the Future. Wetland Crop Reed Reed is also burned or made into biogas without competing with food crops.41Fens for the Future. Wetland Crop Reed42Mires and Peat. The utilisation of reed (Phragmites australis): a review
The trade-off is plain: the benefits come from dense growth, which is also what harms biodiversity. Native reed gives many of them without the takeover. Removing invasive reed may call for replanting the shoreline, and the right decision depends on your site’s goals.
Cut reed can find a use. Harvested winter stems can be mulch or compost if they carry no seed, but don’t spread fresh pieces of underground stem. Some regions buy reed for thatch.
Rules on Planting and Removing Reed
Minnesota proposed listing the non-native subspecies as a prohibited invasive species, but the rule would not apply to the native subspecies.43Minnesota Department of Natural Resources. Non-native subspecies of Phragmites: Frequently asked questions about proposed rule change So correct identification matters before you act. Check state rules before buying ornamental grasses or treating a wetland. Rules differ by state and province: some ban sale and planting, while others focus on transport or required control.
Locally, look at state invasive species lists, whether wetland or shoreline work needs a permit, and whether herbicide applicators must be licensed. Many invasive programs also take reports of new patches.