Giant Reed
Arundo donax L.

Miller, James H. 2003. Nonnative invasive plants of southern forests: a field guide for identification and control. Gen. Tech. Rep. SRS–62. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 93 p.

Plant. Giant reed grass, cornlike stems, thicket forming in distinct clumps to 20 feet (6 m) in height, with gray-green and hairless stems, long-lanceolate leaves alternately jutting from stems and drooping at the ends, and large plumelike terminal panicles. Seed infertile. Spreading from tuberous rhizomes. Dried grass remaining standing in winter and spring.

Stem. Somewhat succulent and fibrous, with round cross section to 1 inch (2.5 cm). Solid jointed every 1 to 8 inches (2.5 to 20 cm) and covered by overlapping leaf sheaths. Gray to yellowish green. Initially white pithed and becoming hollow between joints. Old stems sometimes persistent into the following summer.

Leaves. Alternate, cornlike, long lanceolate with both surfaces hairless, and clasping stem with conspicuous whitish base. Eighteen to thirty inches (45 to 76 cm) long and 1 to 4 inches (2.5 to 10 cm) wide near base. Margins and ligule membranous (about 1 mm). Midvein whitish near base becoming inconspicuous towards tip. Veins parallel. Sheaths overlapping, hairless, and semiglossy.

Flowers. August to September. Terminal erect dense plumes of whorled stemmed flowers to 36 inches (1 m) long. Husks hairy, membranous with several veins, and greenish to whitish to purplish.

Seeds. October to March. Dense terminal plume, spindle-shaped, densely hairy. Grain never appears.

Ecology. Occurs mainly on upland sites as scattered dense clumps along roadsides and forest margins, migrating from old home plantings by displaced rhizome fragments. Persistent infestations by dense branching tuberous rhizome growth. Probable spread by movement of stem parts in soil or by road shoulder grading. Plants believed to be sterile and not producing viable seeds.

Resembles golden bamboo, Phyllostachys aurea Carr. ex A.& C. Rivière, another large grasslike plant that is woody in character. Closely resembles common reed, Phragmites australis (Cav.) Trin. ex Steud., which has similar large hairy seed heads, but not erect and fanned in a loose plume, and which occurs mainly near swamps, marshes, and wet habitats.

History and use. Introduced from western Asia, northern Africa, and southern Europe in the early 1800s. Ornamental.

Recommended control procedures:

Thoroughly wet all leaves with one of the following herbicides in water with a surfactant (September or October with multiple applications to regrowth):

• A glyphosate herbicide as a 2-percent solution (8 ounces per 3-gallon mix)
• Arsenal AC* as a 1-percent solution (4 ounces per 3-gallon mix)
• A combination of the two herbicides

*   Nontarget plants may be killed or injured by root uptake.

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