Seasonal Cycle: Stands of common reed are established through
dispersal of seeds or pieces of underground stems called rhizomes. Once established,
stands grow predominantly by sending up new shoots each spring from existing rhizomes, or
from above ground runners called stolons. If an aerial shoot is knocked over, it can act
like a rhizome, taking root and producing new shoots. This invasive grass can turn year
after year, and some stands are believed to be 1,000 years old. The purplish flower head
turns grey and fluffy as it goes to seed by August. Leaves die and fall off at the end of
the season, leaving the familiar tan stalks and plumes that remain standing through winter
and eventually decay.
Distribution: Common reed grows in temperate zones all
over the world, and can be found in every state in the United States. It is common in the
Northeast. Contrary to popular thought, common reed is native to America; remains of it
have been found in 3,000-year-old peat deposits from Connecticut tidal marshes. However, a
non-native strain of Phragmites australis may have been imported in the early 1900s.
Other points of interest: The word phragmites comes
from the Greek word phragma, which means fence. It refers to the impenetrable masses of
common reed that often form continuous belts in roadside ditches and along upper borders
of salt marshes. The largest known stand occupies 7,000 acres in the Hackensack Meadows
adjacent to New York City. Although common reed was generally thought to have low wildlife
value, preliminary research indicates otherwise. Common reed is part of the diet for geese
and field muskrats that eat the rhizomes. It particularly attracts redwing blackbirds and
sparrows that use it for cover and nesting.
Control: Common reed has become more widespread due to
human-induced changes in nutrient and salinity levels. It grows at rapid rates, displacing
more diverse marsh vegetation, and has come to symbolize marsh degradation. However,
it must be understood that aggressive common reed growth is a symptom of environmental
imbalance, and not the cause. Common reed can be a natural, non-invasive, part of the
landscape in undisturbed areas.
The first step in containing its spread is to minimize land
disturbances (particularly those involving erosion and sedimentation), fluctuating
water levels, nutrient loading (especially nitrates) and pollution. Often, reintroduction
of tidal flow to coastal marshes helps to limit its growth. Although the role of seeds in
establishing new colonies is uncertain, careful disposal of common reed plumes, as from
decorative floral arrangements, is recommended.
Herbicide control is a two-year, two-step process at the very
least. Stands can be treated with Rodeo, the herbicide of choice for work in wetlands. It
is most effective when applied in the early fall when nutrients are being displaced from
the leaves and stems for storage in rhizomes. A permit from DEP (Department of
Environmental Protection) is required to purchase and/or use Rodeo in Connecticut
wetlands.
In the winter, dead culms can be cleared by controlled fire
or cutting/mulching to open the area for desired species. The process usually needs to be
repeated in the second year to reduce the number of remaining plants, and repeated every
three to five years after that. Mechanical cutting may also contain it, and recent efforts
with black plastic have had some success. In any case, there is no easy solution to the
control of this aggressive species.
Additional information sources:
A Field Guide to Coastal Wetland Plants of the Northeastern
United States. Ralph W. Tiner, Jr. The University of Massachusetts Press, Amherst
1987.
Wetlands – Audubon Society Nature Guide. William A.
Niering. Chanticleer Press, Sew York 1987.
For more detailed information: Natural Areas Journal, 1994.
Vol. 14, pp. 285-294. Phragmites australis (P. communis): Threats, Management and
Monitoring. M. Marks, B. Lapin, and J. Randall.
Diagnostic information: Flowers: dense, many branched
terminal inflorescence (panicle 8-16 inches long) with silky hairs longer than lemrnas;
spreading and ascending branches are purplish when young, white or brown at maturity.
Leaves: long, flat, and up to 2" wide, grayish-green, tapering, distinctly, arranged
in two ranks; sheaths open with ligule at junction of blade. Stems: round, hollow, and
upright; persistent throughout fall and winter.
This fact sheet has been prepared by The
Nature Conservancy Connecticut Chapter
