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Montana Field Guide

Montana Field Guides

Smooth Brome - Bromus inermis
Other Names:  Awnless Brome

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 0

External Links

General Description
Rhizomatous perennial. Stems 30–130 cm. Leaves: blades 4–12 mm wide, often with a “W” wrinkle about halfway along the leaf blade. Inflorescence a narrow panicle 7–18 cm long. Spikelets 15–30 mm long, with 8 to 15 florets. Lemmas awnless, 2 mm or less long when lemmas glabrous or 3–10 mm long when lemmas hairy (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

MT plants are the native subspecies pumpellianus and non-native inermis.

Diagnostic Characteristics
The ascending or stiff branches of the open panicle are a key characteristic distinguishing Bromus inermis and Bromus erectus from a group of similar native bromegrasses. The awnless lemmas, from which the species derives its Latin name, distinguish Bromus inermis from both the introduced and similar Bromus erectus and from the native Bromus inermis subsp. pumpellianus.

Species Range

Range Comments
Introduced throughout most of North America, whereas native populations (Bromus pumpellianus) occur at higher latitudes and elevations through much of Canada and the Pacific Northwest region of the U.S. (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 532

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Roadsides, pastures, meadows, and grasslands from low to middle montane elevations (Lavin in Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).)

  • Additional ReferencesLegend:   View Online Publication
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    • Blankespoor, G. W., and E. A. Larson. 1994. Response of smooth brome (Bromus inermis Leyss.) to burning under varying soil moisture conditions. American Midland Naturalist 131:266-272.
    • Lesica, P. 1997. Monitoring density and colony size of Smooth Brome at Comertown Preserve: Baseline Report. Various pages and figures.
    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • Weerstra, A. B. 2000. Control options for smooth brome (Bromus inermis) in the Rumsey Ecological Reserve: A review and summary of relevant research and experiences of practitioners. Submitted to: Public Lands Division, Sustainable Resources Development, Red Deer, Alberta. 42 pp.
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Citation for data on this website:
Smooth Brome — Bromus inermis.  Montana Field Guide.  .  Retrieved on , from