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Phragmites

Invasive Plant of the Month: September 2012

Phragmites (Phragmites australis)


Also Known As

Common reed, Danube grass

General Description

Phragmites is a perennial grass that is native to Asia and Africa. It can form dense stands that include both new growth and dead stems from previous years. Similar in appearance to giant reed (Arundo donax), phragmites can be distinguished by its leaf bases, which are attached by narrow sheaths and do not clasp the stem. Several native phragmites species exist in the United States and are often extremely difficult to distinguish from the exotic species. Phragmites reproduces by seed and by creeping rhizomes.

Growth Habit

Phragmites produces thick, hollow cane-like stems that are approximately 1 inch in diameter and can reach up to 20 feet tall. In the autumn, the plant turns tan, the leaves drop off, and only the fluffy plume remains.

Leaves

Long, narrow leaves have smooth margins and gradually taper toward the tip. Leaves are 6–24 inches long and 0.5–2 inches wide at the base.

Flowers

Flowers occur in large, feathery flower heads that are 6–20 inches long and golden or purple in color. Flowering occurs from July to October.

Seeds and Fruit

Tiny seeds are about 0.05 inches long.

Habitat

Phragmites is typically found in or near wetland areas, and along roadsides, riverbanks, lakeshores, and ditches. It can grow in water up to 6 feet deep and can tolerate mostly dry areas.


Additional Resources

Species Identification and Characteristics
BugwoodWiki
Distinguishing Native and Exotic Forms of Common Reed in the US: Plant Conservation Alliance (PDF)
Invasive.org Images and Overview
Invasive Phragmites: What Is It and What Can We Do? (VIDEO)
Plant Conservation Alliance Fact Sheet
USDA Forest Service Fact Sheet (PDF)

Management and Control Resources

Best Management Practices: King County Noxious Weed Control Program (PDF)
Cornell University's Phragmites Diagnostic Service
USDA Forest Service Species Information

 

Past "Invasive Species of the Month" Profiles