Ontario Weeds: Smooth brome

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

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

Name: Smooth brome, Bromus inermis Leyss.,

Other Names: BROIN, brome inerme, Brome grass, brome

Family: Grass Family (Gramineae)

General Description: Perennial spreading by seed and by dark-coloured underground stems (rhizomes).

Photos and Pictures

Smooth brome


Smooth brome. A. Plant.
Smooth brome. A. Plant.

Stem and leaf-base characteristics of a typical grass.
Stem and leaf-base characteristics of a typical grass.

Stems & Roots: The underground rhizomes have nodes or joints and internodes and blunt tips. They produce roots and branches from the nodes. Some branches turn upwards to emerge as leafy stems. Other remain underground producing still more branches. Each internode is covered by a large brown to blackish, dry scaly sheath giving the whole rhizome a dark colour. Stems, erect, 20-100cm (8-40 in.) tall, leafy.

Flowers & Leaves: Leaves 10-40cm (4-16 in.) long, pointed, flat, 5-12mm (1/5 - 1/2 in.)wide, and usually marked with a light green or wrinkled "tattoo" resembling the letter W near the middle of the blade; leaf sheath closed (margins united) except for a small V-shaped notch at the top; ligule a membrane 1-2 mm (1/25 - 1/12 in.) long; auricles absent or very short and rounded. Inflorescence or "seed head" is a branched panicle, 10-20cm (4-8in.) long, the stiff branches spreading when pollinating but afterwards for erect and tighter. Each spikelet 2-2.5cm (4/5 - 1in.) long, without awns (hence the name "smooth"), or with awns not over 2mm (1/12in.) long, and 5 to 9 flowered (having 5 to 9 fertile florets which become the individual "seeds"). Flowers from June to September.

Habitat: Smooth brome is widely cultivated as an excellent hay an pasture grass, and as a soil cinder along roadsides, eroded banks, etc., throughout Ontario. Bit it often persists after cultivation and may infest succeeding crops, gardens and lawns. Old stands may become sod-bound, producing many short, leafy stems but few or no seed heads.

Similar Species: It is distinguished by the letter W on some lead blades, its closed leaf sheath, the absence of distinct auricles, its blunt-tipped rhizomes with dark brown scaly sheaths as long as or longer than each internode and its branched, erect panicle with fairly large smooth spikelets.

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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For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 01 June 2000
Last Reviewed: 01 November 2003