Tuesday, June 3, 2014

Plant Profile - Phragmites

Invasive plant species can become a "giant" problem for resource managers.  One true "giant", as far as invasive wetland and aquatic plants go, can be found on EVERY continent except Antarctica and is found highly invasive throughout North America.  This particular plant has two native varieties which occur in various parts of the United States, however a very similar invader variety from Europe can be found throughout much of the same territory and cause a variety of problems.  Its scientific name alone means "southern plant with fence-like growth"....

Phragmites australis, also called the "common reed" because of its wide distribution, is a perennial wetland species that grows from a large, thick root system buried deep in the sediment of areas of fresh to brackish water.  While not completely sure how exactly the plant got here, the invasive variety was most likely introduced to the Atlantic Coast in the late 1800s and the species has since spread throughout the United States and Canada except for the coldest reaches in Alaska and the Nanvut Territory.  Phragmites has been widespread in the northeastern US for decades and is quickly spreading west into the Great Plains prompting multi-million dollar control efforts in various states.

Figure Credit:  Delaware Division of Fish and Wildlife
Phragmites outcompetes and  replaces native plants by growing much taller and faster than others, sometimes reaching 20 feet in height! The invasive variety of Phragmites sprouts, survives, and grows better in fresh and saline environments than native phragmites making it a huge threat to native wetland vegetation along the coast. Phragmites has even been called an "ecosystem engineer" because numerous changes can occur when phragmites invades an area and replaces other vegetation, much to the benefit of the plant. Invasive phragmites invasions lead to decreased plant diversity, changes in soil properties andsedimentation rates, and alter habitat use and food webs.  Phragmites spreads primarily by vegetative means, making management extremely difficult.  The plant produces dense monotypic stands of clones, or plants that are genetically identical to one another. Clones are long-lived and can reportedly live for 1,000 years or more!

Flowers of Phragmites.
Phragmites produces stout, erect, hollow above-ground stems from rhizomes that persist when stems and leaves die back during winter. Stems are usually unbranched and bear leaves that are arranged in an alternate manner along the top half of the stem. Leaf blades are blue-green to green in color and have margins that are somewhat rough. Leaves are flat at maturity and measure 4 to 20” long and 0.4 to 2” wide.  Phragmites is also easily distinguished by it's large, showy flowers that grow as long as 16 inches.  These flowers are mostly purplish in color and appear in late July and August.

For information on the management of Phragmites, visit our Best Management Practices Handbook Chapter 15.11, page 171.

For a distribution map of Phragmites, visit the USDA plants database

For more on the Aquatic Ecosystem Restoration Foundation, visit our website.

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Stay tuned for more of the latest in aquatic plant science, management, and innovation!

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