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Washington State Weeds

Common Reed

common reed

 Phragmites australis  • Class B

Family Name: Poaceae family (poh-AY-see-ee)
Common: Grass family
Genus: Phragmites (frag-MY-tees)
Meaning: A screen or temporary defense
Species: australis (aw-STRAL-iss)
Meaning: Of or from the south, or Australia

Phragmites or common reed is a very large, perennial grass that grows up to 15 feet tall.

It has large hollow stems, which produce leaves up to 16 inches long along most of their length.

Short papery bracts, called ligules, grow from the leaf where it bends out from the stem and are yellow or greenish in color.

It produces dense feathery flower heads 8 to 16 inches long. 

 Why Is it a Noxious Weed?

Common reed will colonize and displace the other plants in a wetland community, often forming dense monocultures.

It displaces wildlife because it alters the wetland environment so dramatically.

Water quality is also deteriorated, because water flow or circulation is adversely affected by this species. 

Where Does it Grow?

Seedlings may be produced on nearly any site that has some surface water, even brackish or salt water. It is typically found in or near wetlands. 


Below the water line, the plant’s root system secretes an acid so toxic that it causes the protein structure in nearby plant roots to rot away, killing off all neighboring plant life so that it can spread to new areas. 

Common Reed reproduces both by large quantities of wind and water dispersed seed and by rhizomes. Once a stand is established it spreads primarily through vegetative means. 

Control Options:
  • Cutting has been used successfully for control. Cuttiing at the wrong times, may increase stand density. However, if cut just before the end of July, most of the food reserves produced that season are removed, which reduces the plant's strength. This process must be repeated for several years to be effective. Care must be taken to remove cut shoots to prevent regrowth. 
  • Care must be taken not to produce new plants when clearing common reed infestations. The entire plant material should be removed to prevent rhizomes from producing new plants.
  • Since Common Reed is found in wetland areas, the use of an herbicide formulated for aquatic settings is required. Please note that aquatic herbicides are restricted for use in Washington State to licensed applicators only. 

More Information:

For more information on this noxious weed Download our Flyer or visit Washington State Noxious Weed Control Board Here


More Pictures:  

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