Phalaris arundinacea is a cool-season perennial grass that grows to 6 ft. (1.7 m) tall. Reed canarygrass is variable in morphology, so characteristics may depend upon the habitat.
Foliage
Leaf blades are flat, 1-4 ft. (0.3-1.2 m) long, up to 0.75 in. (1.9 cm) wide, glabrous and taper gradually. The ligule is membranous (transparent) and long.
Flowers
The spreading flower/seed heads arise from hairless stems and can be green, purple, or brown in color and usually 3-6 in. (7.6-15.2 cm) in length. Flowering occurs from May to July.
Fruit
The inflorescence color changes from green to purplish to tan as the seeds mature. There are both sterile and fertile lemmas.
Ecological Threat
Phalaris arundinacea can quickly dominate wetlands, ditches, prairie potholes, and other sites with moist soil. It can exclude all other vegetation and is extremely difficult to eradicate once established. Nativity of this plant is debated; it is native to Europe and possibly parts of Asia, but it may also be native to the northwestern United States. Aggressive behavior that is exhibited in many parts of the central and western United States may be a result of escaped cultivars that were bred for vigor and quick growth.