Common Reed
Phragmites australis
Washington State Classification
Class B — Control Required (Designated)
Common reed forms dense, monotypic stands in wetlands.
Required control in Region 1 (all western Washington counties)
Quick Reference
Identification
Growth Habit
It is a large perennial grass with creeping rhizomes and distinctive feathery, plume-like flowerheads. Common reed looks very similar to our native, genotype of Phragmites australis, which is being outcompeted by the invasive genotype.
Leaves
The leaves are lance-shaped and 8 to 16 inches long and 1/5 -1.5 inches wide. The leaf blade is smooth. Loose blades will twist in the wind to one side.
Flowers
The flowers are dense and silky. Floral spikes are tawny, purplish and 1 to 16 inches long.
Impact
Common reed forms dense, monotypic stands in wetlands. Wildlife is displaced when wetland hydrology, structure and function are altered. Water quality deteriorates when water flow or circulation is adversely affected by this species.
Ecology & Spread
Habitat
Common reed is found in disturbed and non-disturbed sites that hold water, including roadside ditches and depressions. It is typically found in or near wetlands. Please click here to see a county level distribution map of common reed in Washington.
Spread Mechanisms
Reproduction
Common reed is a clonal grass species that reproduces both vegetatively and by seed dispersal.
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Control Methods
Mechanical
- Cutting has been used successfully for control. Multiple cuttings of common reed at the wrong times of the year may increase stand density. Cutting can be used for successful control by cutting it just before the end of July when most of the food reserves produced that season are removed and the aerial portion of the plant reducing the plant’s vigor. This regime may eliminate a colony if carried out annually for several years. Care must be taken to remove cut shoots to prevent re-growth. Disking can be used but it can result in an increase of plants since rhizome fragments can sprout new plants. Burning does not reduce the growing ability of common reed unless the roots are burned, which is difficult to achieve.
Biological Control
- Grazing has not been successful since cattle consume only the above ground portions of the plant.