Giant Reed

Arundo Donax

Giant reed is a perennial grass that can grow to 25+ feet tall. Originally imported to the US as an erosion control and horticultural plant in the 1800s, it has escaped and moved into many riparian areas in the west. It is native to the Mediterranean region and eastern Asia.

It spreads by rhizomes and stem nodes and can form large clumps resembling bamboo. It grows in full sun and in lightly shaded areas and is very drought tolerant.

The leaves can be 2 inches wide and up to 36 inches long. Stems are ¼ -2 inches wide.

Its distinctive auricles clasp the stem. The ligules are large and papery with small hairs along the margin.

The flowers are arranged in a large plume 1-2 feet long. Within North America, it is not believed that the seeds are viable.

Giant reed forms huge colonies along waterways. It disrupts the water flow, increases sedimentation, and changes the structure of water channels that can lead to erosion. Dead and dry stands can pose a fire hazard.

Colorado has less than 500 known locations and this List A noxious weed needs to be completely eliminated. Because it easily spreads by plant fragments removal is not an option. Use of a systemic herbicide will give the best control.

RESOURCES

Noxious Weeds of Colorado 14th Addition
Colorado Weed Management Association