Family: Poaceae

Arundo donax (arundo, giant reed) is a tall, bamboo-like grass native to parts of Asia and the Mediterranean region. It was introduced widely for erosion control, windbreaks, and as an ornamental plant. Growing up to 30 feet tall, arundo forms dense stands along waterways and disturbed areas. Its rapid growth and deep rhizome network allow it to outcompete native vegetation, altering soil chemistry and displacing wildlife habitat. It spreads primarily through fragments of its rhizomes, which can easily establish new colonies when carried by water or machinery.

In Hawaiʻi, arundo is considered a serious invasive species and is not recommended for planting. It is naturalized on several islands and poses a high fire risk due to its dry, fibrous stems, which can fuel fast-moving wildfires. The plant also consumes large amounts of water, reduces stream flow, and increases erosion once established. Because of its aggressive nature and environmental impacts, prevention and early removal are the best strategies to control its spread. Planting native or non-invasive alternatives is strongly encouraged.

High Risk Traits:

• Broad climate suitability (cool temperate to tropical)
  
• Naturalized and invasive in many regions globally
  
• Forms dense stands that displace native vegetation (environmental weed)
  
• Toxic to humans, causing dermatitis and allergies
  
• Highly flammable and increases fire risk
  
• Tolerates a wide range of soils and high salinity
  
• Reproduces aggressively via rhizomes and stem fragments
  
• Fast-growing, reaching maturity in under a year
  
• Spread by water, wind, machinery, and human activity
  
• Resprouts vigorously after cutting or burning

Low Risk Traits:

• Young growth is palatable to grazers
  
• Not shade tolerant (requires full sun)
  
• Can be controlled effectively with herbicides