The Weed of the Month for November is a warm season perennial semi-aquatic grass species called non-native Phragmites (Phragmites australis ssp. australis). Non-native Phragmites threaten wetland areas and can outcompete native plant species with its prolific growth and dense growth habit.
Non-native Phragmites reaches a height of 15 feet. It has a ridged, hollow stem with a rough texture. The blue-green leaves are 15-20 inches long by one inch wide and remain on the stem through the winter. It forms purplish flowers at the tips of the stems, and produces thousands of grayish seeds that have a fluffy appearance. The plant forms a dense monoculture both by seed and by vigorous roots that can spread more than 10 feet laterally and several feet deep.
Non-native Phragmites grows in a variety of aquatic to semi-aquatic habitats in Minnesota. It colonizes disturbed areas such as roadsides, gravel pits, shorelines, wetlands, marshes, flooded areas, and streambanks. Seeds are disbursed through wind, water, animals, and human activity. Phragmites also reproduce be above and below ground stems that send up new shoots to form dense clumps. The plant can regenerate from root fragments that are moved by flooding or contaminated soil.Management of non-native Phragmites requires commitment and multiple years of monitoring.
More information is available at Great Lakes Phragmites Collaborative.