Invasive Phragmites

Phragmites australis

Characteristics

Found throughout the United States, Phragmites australis is yet another invasive that plagues the Great Lakes region. It should be known that there is a native subspecies of phragmites found in Michigan, Phragmites australis subsp. americanus, which is often confused with its invasive counterpart. Although invasive phragmites infestations in the Upper Peninsula are primarily concentrated along the northern shore of Lake Michigan, there have been a few isolated sightings in the Keweenaw, and these sightings may grow in number as the surveying for this species increases. This grass invader grows readily in wetlands, ditches, swales, and along stream and pond banks. Common identifying features include:

• grows to heights ranging from 6-15 feet
• leaves are flat and smooth growing 10-20 inches long, 0.5-1 inch wide with hairy ligules 
• leaves are green to grayish/bluish-green in color
• stems are upright, rigid, and hollow; persistent in winter; lengthwise ridging along stem
• flowers form dense, branched clusters at the end of each stem appearing feathery at maturity
• seeds found in unison with white hairs
• large and robust root system

As previously mentioned, native phragmites is often confused as an invasive, and as a result, many have unknowingly removed native stands. In order to avoid this, look for the distinguishing characteristics between the two. Invasive phragmites often have leaves that appear grayish or bluish-green compared to the native species which appear green to light green in color. Furthermore, the stems of invasive phragmites are typically a dull greenish-tan color, whereas native stems often display a reddish or purplish tone.

For more information, visit the Midwest Invasive Species Information Network (MISIN) or the Great Lakes Phragmites Collaborative. 

KISMA Management Practices

Phragmites can quickly spread through Keweenaw marshes and wetland areas, robbing fish, plants, and wildlife of nutrients and space; blocking access to the water for recreational purposes; ruining shoreline views; and posing a fire hazard through the accumulation of dead stalks. The plant is also able to adjust its growth based on environmental conditions and survive stagnant, oxygen poor, or salty conditions. Phragmites is spread by wind-borne or animal-borne seeds, or through intentional introduction. More commonly, Phragmites spreads through above ground root structures called stolons or through its underground rhizomes. Due to its (not so) great ability to establish a site and form dense monocultures, phragmites management can often prove difficult and costly. See the following steps and this guide to phragmites management:

1. determine whether the plants are native or invasive phragmites
2. if invasive, hand removal may be possible if the invasion is small enough; wearing gloves, pull or cut stems just below the soil surface at least twice during the growing season, but especially before the flower heads fully develop
3. with larger patches of invasive phragmites, hand removal is usually not possible and chemical treatment is likely necessary
4. chemical treatment may (and usually will) require one or more permits from local, state, and federal authorities
5. mechanical treatment such as mowing or cutting is recommended at least two weeks after chemical treatment, as it will promote native plant regeneration
6. monitor impacts of performed treatment and identify areas that require follow-up treatment
7. this process will likely need to be repeated over several years in order to fully eradicate phragmites from the site

Note: It is unlikely and unrealistic for the average person to perform widespread chemical and mechanical management of phragmites. The best thing to do is to consistently monitor your local area for new signs of invasion in order to address the problem before the plant fully establishes a population. If you do happen to come across such a site, reach out to your local invasive species management group which will have the proper resources and connections to properly handle the invasion.

Native Alternatives

If you do happen to remove invasive phragmites on your property, it would be a good idea to plant natives in its absence. The appropriate native replacements depend on the type of wetland, but native willow (Salix spp.), red-osier dogwood (Cornus sericea), and sweet gale (Myrica gale) are good options as well as other native wetland grasses and reeds.