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Report an Invasive Species

Giant Reed

Giant Reed

Giant Reed

(Arundo donax)

Priority: -  Prevent

Tags: Agricultural | EDRR

Identification and Reproduction


  • Giant reed is a perennial reed that can grow over 6 m tall. 
  • Stems are hollow and have a diameter of 2-3 cm. 
  • Leaf blades are long, flat, alternating along the stem and up to 0.5 m long. They are often green but can be variegated and have white stripes along the blade. 

  • Seeds heads are long and plume-like, around 30-65 cm in length. This plant flowers from August to September.


  • Seeds are rarely produced and if they are they are often not fertile. 
  • Giant reed reproduces vegetatively by tough, fibrous underground rhizomes that forms thick knotty mats within the soil surface. 
  • A root fragment as small as 5 cm can resprout. 
  • It is common for giant reed roots to break apart during floods and be carried downstream. 

Habitat & Ecology

  • Giant reed dominates moist, well-draining sites, often along ditches, rivers, lakes and floodplains. 
  • It is well adapted to various conditions but thrives in riparian and wetland systems.
  • This plant also has a high tolerance to heavy metals. 



  • This weed is an extremely fast growing plant, growing nearly 10 cm a day. 
  • It has very little food and habitat value for wildlife species. 
  • Over-crowds native vegetation species, including trees and grasses. 
  • Acting as an ecosystem engineer it alters plant communities drastically. 
  • It absorbs available water and creates a dam effect in riparian areas because of its spreading root mass. 
  • Giant reed also poses as a fire treat, as they are extremely flammable. 


Prevention is a high priority for this plant. 

  • Do not plant giant reed. 
  • It is now illegal to provide, sell or domestically transport giant reed in Canada. 
  • If you are anyone you know has giant reed on their property contact the CFIA for eradication steps. 


Check out the Canadian Food Inspection Agency's datasheet on Giant reed here.

Download the CFIA's factsheet of Giant Reed here

Header photo (Forest and Kim Starr).