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The P&PDL Picture of the Week
for 6 January 2003



Common Reed - Phragmites

Glenn Nice, Botany and Plant Pathology, Purdue University

This member of the grass family (Poaceae) looks more like bamboo than a grass (figure 1). It also looks like it should belong in Asia, not in downtown Indianapolis. You probably have seen this grass in ditches as you drive by or if you have had a chance to make it up to the Gary or Chicago area you will see copious amounts along canals and ditches although maybe not quite this big.

Dr. Markus Scholler, Nick Harby, and I (Glenn Nice) went to investigate a report by Nick of a stand of huge grass in the middle of Indianapolis. What we found was a stand of very large common reed (Phragmites australis (Cav.) Steud. or Phragmites communis Trin.) growing in an old canal. Story from property owners next to the impressive stand stated that it had been there for many years.

This reed-like grass can have culms anywhere from 5 to 15 feet tall (figure 2). The formation of rhizomes can form large colonies (figure 3) in areas where water will stand some of the year such as canals and ditches. Blades are lanceolate and can be 6 to 12 inches or more long, 1/3 to 2 inches wide. Ligules are a ring of hairs up to 3/10 long (figure 4). Panicles are 6 to 12 inches long and spikelets are crowded. Seed are wind dispersed giving the seed head a fluffy look (figure 5).

Once common reed is established it is very difficult to control. Prevention is the most effective control. This can be aided by reducing land disruption, pollution through runoff, and erosion.

Once established, cutting and prescribed burning can deplete underground reserves and eventually control common reed. The cutting or/and burning will have to be repeated for more than two years.

Some research has reported that a chemical with prescribed burning would promote other grasses and eventually choke the common reed out. One such suggested method of chemical control is to cut the grass in the fall (being careful to collect the seed so not to spread the problems) and immediately applying a 25% solution of glyphosate into the hollow stems. Be sure to select a herbicide that is labeled for a wetland situation. A permit may be required for application.

Click on the small image to view a larger image.

Nick Harby and I standing in the thick of common reed
Common Reed looking up the stem
Dense growth of common reed culms
The ciliate ligule of common reed
Common reed seed head
Downtown Indianapolis within sight

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Last updated: 6 January 2003/amd
The Plant & Pest Diagnostic Laboratory at Purdue University