Photo Credit: John D. Byrd, Mississippi State University, Bugwood.org
Giant reed leaves. Photo Credit: David J. Moorhead, University of Georgia, Bugwood.org
Giant reed seedheads. Photo Credit: Rebekah D. Wallace, University of Georgia, Bugwood.org
Also known as: Spanish reed, giant cane, giant reed grass, elephant grass
Giant reed is a thirsty plant! It uses three times as much water as native plants. It can clog culverts, destabilize riverbanks, and outcompete native shrubs and trees.
For a more detailed description, download the Giant Reed Best Management Practices factsheet.
|Perennial (life cycle lasts more than one year)
|Early Detection and Rapid Response species:
|Up to 20 feet (6 meters) tall
|Leaf & Stems Description:
|Grey-green leaves are flat and taper to a fine point. Each leaf can grow up to 2 feet (0.6 meters) long. They clasp stems in a heart shape.
The leaves grow off a bamboo-like stem or cane.
|Flower & Seeds Description:
|Its cream-colored flowers grow in large plumes from the ends of its stems.
In North America, flowers either don’t form seeds or form infertile seeds.
|March to September
How it spreads:
- Spreads vegetatively through rhizomeRhizome A continuously growing, horizontal underground stem. fragments since plants do not produce viable seed in North America.
- Flooding and erosion along infested riverbanks dislodge rhizome fragments and move them to new locations.
- Stems that have fallen over or dislodge from the soil can also produce new plants.
- Giant reed is commonly found in riparian areasRiparian Areas Areas of land that occur along the edges of rivers, streams, lakes, and other bodies of water., floodplains, irrigation ditches and along roadsides.
- It grows well in moist areas, especially thriving in sandy or well-drained soils and plenty of sun.
- Giant reed develops dense stands which displace native vegetation, diminish wildlife habitat, and increase the risk of flooding.
- Its canes are highly flammable which increases the risk of wildfires.
- Mature stands remove large amounts of water from the ground.
What you can do about it:
- If you think you’ve found giant reed anywhere in Oregon, please report it to the Oregon Invasive Species Hotline.
- Manual: Manual control is limited to younger, smaller patches due to mature stand’s extensive, tough underground rhizome network.
- In the spring when the canes are small and the ground is moist, plants can be removed with shovels and pickaxes.
- It is vital that all the root fragments are removed from the soil and all plant materials are disposed of in tied plastic bags in the trash – not yard debris or home compost.
Giant reed looks like common reed (Phragmites australis). Giant reed is much taller than common reed. It also has wider leaves, thicker stems, and large rhizomes than common reed.
It also resembles many bamboo species (Phyllostachys species). The best way to tell these plants apart is by examining how each leaf attaches to the stems. Giant reed’s leaves attach around the entire stem.
Noxious Weed Listing:
- University of California, Weed Research & Information Center: Giant reed