Common reed, or Phragmites,
is a tall, perennial grass that can grow to over 15 feet in height. In North
America, both native phragmites (Phragmites australis ssp. americanus Saltonstall,
P.M. Peterson & Soreng) and introduced subspecies are found. Introduced Phragmites forms
dense stands which include both live stems and standing dead stems from previous
year’s growth. Leaves are elongate and typically 1-1.5 inches wide
at their widest point. Flowers form bushy panicles in late July and August
and are usually purple or golden in color. As seeds mature, the panicles
begin to look “fluffy” due to the hairs on the seeds and they
take on a grey sheen. Below ground, Phragmites forms a dense network
of roots and rhizomes which can go down several feet in depth. The plant
spreads horizontally by sending out rhizome runners which can grow 10 or
more feet in a single growing season if conditions are optimal.
Please see the table
below for information on distinguishing betweeen native and introduced Phragmites.
Once introduced Phragmites invades
a site it quickly can take over a marsh community, crowding out native plants,
changing marsh hydrology, altering wildlife habitat, and increasing fire
potential. Its high biomass blocks light to other plants and occupies all
the growing space belowground so plant communities can turn into a Phragmites monoculture
very quickly. Phragmites can spread both by seed dispersal and by
vegetative spread via fragments of rhizomes that break off and are transported
elsewhere. New populations of the introduced type may appear sparse for the
first few years of growth but due to the plant’s rapid growth rate,
they will typically form a pure stand that chokes out other vegetation very
IN THE UNITED STATES
Phragmites occurs throughout the lower 48 states
and southern Canada. It has been reported to be invasive in natural areas
in 18 states including Colorado, Connecticut, Delaware, Georgia, Indiana,
Kentucky, Maryland, Michigan, North Carolina, New Hampshire, New Jersey,
New York, Ohio, Pennsylvania, Tennessee, Virginia, Vermont, and Wisconsin,
and the District of Columbia.
HABITAT IN THE UNITED STATES
nontidal brackish and freshwater marshes, river edges, shores of lakes and
ponds, roadsides, disturbed areas.
Preserved remains of native Phragmites that
are 40,000 years old have been found in the southwest indicating that it
is a part of the native flora of that region. In coastal areas, preserved
rhizome fragments dating back 3000-4000 years have also been found in salt
marsh sediments indicating that it is also native to these habitats. Native
American uses of Phragmites include use of stems for arrow shafts,
musical instruments, ceremonial objects, cigarettes, and both leaves and
stems for constructing mats.
Introduced Phragmites is thought to have
arrived in North America accidentally, most likely in ballast material in
the late 18th or early 19th centuries. It established itself along the Atlantic
coast and over the course of the 20th century, spread across the continent.
In Europe Phragmites is grown commercially and is used for thatching,
fodder for livestock, and cellulose production. It is also declining in parts
of Europe which has been of concern to natural resource managers there. Here
in the United States it is not used for many purposes.
BIOLOGY & SPREAD
While each Phragmites plant
may produce thousands of seeds annually, seed viability is typically low
although there appears to be a great deal of interannual variation in fecundity.
Dispersal to new sites is typically by seed except along rivers and shorelines
where fragments of rhizomes may be washed down to new sites where they can
establish. Along roadsides, rhizomes fragments may also be transported by
heavy machinery between sites. At this time, there is no evidence for hybrid
native/introduced populations occurring in the field.
with large, established, populations of Phragmites are best restored using
herbicides. Other options include mowing and prescribed burning.
At this time no means of
biological control are available in the United States for treating Phragmites infestations.
(e.g., Rodeo®) are the most effective control method for established populations.
If a population can be controlled soon after it has established chances of
success are much higher because the below-ground rhizome network will not
be as extensive. Herbicides are best applied in late summer/early fall after
the plant has flowered either as a cut stump treatment or as a foliar spray.
It is often necessary to do repeated treatments for several years to prevent
any surviving rhizomes from resprouting. When applying herbicides in or around
water or wetlands, be sure to use products labeled for that purpose to avoid
harm to aquatic organisms.
Prescribed burning after the
plant has flowered, either alone or in combination with herbicide treatment,
may also be effective. Burning after herbicide treatment also reduces standing
dead stem and litter biomass which may help to encourage germination of native
plants in the following growing season. Plants should not be burned in the
spring or summer before flowering as this may stimulate growth.
This type of control (e.g.,
repeated mowing) may be effective at slowing the spread of established stands
but is unlikely to kill the plant. Excavation of sediments may also be effective
at control but if small fragments of root are left in the soil, they may
lead to reestablishment.
USE PESTICIDES WISELY: ALWAYS READ THE ENTIRE PESTICIDE LABEL CAREFULLY, FOLLOW ALL MIXING AND APPLICATION INSTRUCTIONS AND WEAR ALL RECOMMENDED PERSONAL PROTECTIVE GEAR AND CLOTHING. CONTACT YOUR STATE DEPARTMENT OF AGRICULTURE FOR ANY ADDITIONAL PESTICIDE USE REQUIREMENTS, RESTRICTIONS OR RECOMMENDATIONS.
NOTICE: MENTION OF PESTICIDE PRODUCTS ON THIS WEB SITE DOES NOT CONSTITUTE ENDORSEMENT OF ANY MATERIAL.
For more information on identification
and control of Phragmites, contact:
- Dr. Kristin Saltonstall; Adjunct
Research Scientist; Horn Point Laboratory; University of Maryland Center
for Environmental Science; ksalton at hpl.umces.edu; Tel: (914) 526-2498
SUGGESTED ALTERNATIVE PLANTS
plant species that are adapted to local conditions should be used in restoration
projects and as a substitute for Phragmites erosion control practices.
How to Distinguish
Native and Introduced Phragmites plants:
It can be difficult to definitively
distinguish native from introduced Phragmites plants without genetic
testing due to the plasticity of the species and its ability to adapt to
a wide range of conditions. However, a number of morphological characteristics
have now been identified that can be used to determine a population’s
type. These characters can be subtle (e.g. color variation) and subjective
making positive identification difficult. Given this, an assignment of native
or introduced status to a population should not be made unless several characters
clearly match the patterns shown in table 1.
Table 1: Morphological characters
useful in distinguishing Native and Introduced Phragmites populations.*
|Lower glume length
|Upper glume length
|Adherence of leaf
|Loose – both
leaves and leaf sheaths are usually dropped as the plant senesces
||Tight – leaves
may drop off but leaf sheaths typically adhere tightly to dead stems
|Stem color (look
under the leaf sheaths, especially in places where the stem is exposed
|Summer – green
to maroon, may have maroon color at the nodes only
Winter – yellow to brown
|Summer – typically
all green with yellowish nodes although some lower nodes may have maroon
Winter – yellow
|Small round fungal
spots MAY be present in late summer and on dead stems
||Extremely rare. Patches
of black filamentous fungi may be seen
||May occur as a monoculture,
often co-occurs with other plant species
||Typically grows as
a monoculture, young newly established populations and those in areas
of high salinity may be less dense
|Yellow-green – usually
lighter than introduced
||Blue-green in most
habitats but may be yellow-green in brackish habitats
MidAtlantic – fresh to oligohaline tidal marshes
Midwest – fens, marshes
to undisturbed sites, dominates brackish marshes along the Atlantic coast,
common along roadsides throughout the U.S.
* This table should not
be used to distinguish between Phragmites populations along the Gulf Coast
where another type of Phragmites, the Gulf Coast type, which looks similar
to introduced Phragmites, is also found.
** Most reliable
characters distinguishing native from introduced Phragmites.
Dr. Kristin Saltonstall, Adjunct Research Scientist,
Horn Point Laboratory University of Maryland Center for Environmental Science,
Jil M. Swearingen, National Park Service, Center for Urban Ecology, Washington,
Jil M. Swearingen, National Park Service, Center
for Urban Ecology, Washington, DC
Dr. Kristin Saltonstall, Adjunct Research Scientist, Horn Point Laboratory
University of Maryland Center for Environmental Science, Solomon, MD
North DE Wetland Rehabilitation Program,
DE Mosquito Control Section,
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