Ontario Weeds: Common reed

Table of Contents

1. Name
2. Other Names
3. Family
4. General Description
   • Photos and Pictures
5. Stems and Roots
6. Flowers and Fruit
7. Habitat
8. Similar Species
9. Related Links

Name: Common reed, Phragmites australis (Cav.) Trin. ex Streud.,

Other Names: phragmite commun, jonc à balais, roseau commun, P. communis Trin.

Family: Grass Family (Gramineae)

General Description: Perennial, reproducing by rhizomes and rarely by seed.

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Photos and Pictures

Common reed. "Flag-like" or "plume-like" inflorescence.

A. Upper portion of stem with leaves, before flowering.

Stem and leaf-base characteristics of a typical grass.

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Stems & Roots: Stems smooth, erect, thick (to 10mm, 2/5in. in diameter), almost woody, sometimes purplish, up to 4m (13ft) high, arising from long, firm, extensively creeping rhizomes; leaf sheaths smooth and hairless with apparently smooth, often purple margins that may overlap or be separate, the margins ciliate with very fine hairs seen only with magnification; collar (junction between leaf sheath and leaf blade) yellowish-green with wrinkled edges, and forming prominent (almost 1mm, 1/25in. high) auricle-like shoulders where its edges join the margins of the sheath: ligule complex, a very short (0.2mm, 1/100in.) yellowish or purplish membrane topped by a dense band of very short white hairs about 0.5mm (1/50in.) long together with a single line of very long, relatively firm hairs about 5-15mm (1/5-3/5in.) long; most of these long hairs soon falling off leaving only a band of short hairs on ligules of older leaves; and the tuft of medium length, straight or kinky hairs arising from the margin of the collar each side of the leaf blade; leaf blades flat and smooth, 5-60cm (2-24in.) long and 0.3-6cm (1/8-21/2in.) wide, very tapered at the tips.

Flowers & Fruit: Inflorescence at first purplish, becoming tawny and nearly dark brown at maturity, 12-40cm (41/2-16in.) long with ascending branches and forming a thick, densely branched, silky panicle; spikelets 10-17mm (2/5-¾in.) long, each with 3-7 seeds; hairs of the rachilla long and white, their abundance giving the whole inflorescence its silky appearance. Flowers from August to September.

Habitat: Common reed occurs both as a native plant distributed widely throughout temperate North America and as a very closely related variety introduced from Europe. It is found in fresh to alkaline marshes, lake-shores, pond margins, ditches, roadsides and fields throughout most of Ontario. The rhizomes are easily spread from place to place by farm and road machinery, and once established, the plant spreads rapidly by these rhizomes.

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Similar Species: It is distinguished by its great height, its stiffly erect, unbranched stems, its large, soft panicles that are purplish when first headed-out but become feathery and turn brownish with age, and by the very dense patches that it forms wherever it grows.

Related Links

... on general Weed topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control

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