Arundo donax

Family

Poaceae – Grass family

Other Names

Giant reed

USDA Code

ARDO4

Legal Status

Colorado Noxious Weed List A

Identification

Lifecycle

Perennial

Growth form

Grass

Flower

Flowers are silver-cream, in 2 foot long panicles

Flowers June-September

Seeds/Fruit

Seeds brown, teardrop-shaped with small hairs.  Most plants in North America do not produce viable seed

Leaves

Leaves alternate, 1-3 inches wide and 1-3 feet long, pale green to blue-green, heart-shaped collar clasps the stem

Stems

Plants are up to 30 feet tall. Stems hollow between nodes

Roots

Rhizomes form a “root ball” which can be several feet long and wide

Seedling

New plants grow from spreading rhizomes

Impacts

Agricultural

Can clog stream banks

Ecological

Forms dense clumps along streams, rivers and canals

Habitat and Distribution

General Requirements

Found in riparian areas and wetlands

Forms dense thickets, can burn intensely

Distribution

Has been found in Colorado in limited areas

Has been used as an ornamental and has escaped

Historical

Native to Europe and Asia

General Requirements

Prefers medium to fine soils

Biology/Ecology

Mode of Reproduction

Reproduces by rhizomes and vegetatively