Smooth Brome

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A non-native grass found across Illinois

Smooth Brome, Bromus inermis, has been reported in every county in the state of Illinois. Smooth Brome is a cool-season, non-native grass. It was widely planted it as a forage grass, so it can be found in fields, prairie restorations, and disturbed habitats. 

Identifying characteristics

One of about 20 species of Brome grasses, Smooth Brome grows about 3 feet tall. Its leaf blades can be a grayish-green on top and green below. They also have a zig-zag or m-shaped crimp in the middle of the leaf that you can feel if you run your fingers along the leaf blade. Smooth Brome has a membranous ligule too.

In the fall, the leaves of Smooth Brome turn a straw color and curl tightly. The leaves then rustle in the wind, making this grass stand out from others in the area.

What do the spikelets look like?

Smooth Brome flowers in early summer, producing a panicle inflorescence. The spikelets are green to reddish in color, smooth, and elongated. While the spikelets of most Brome grasses have awns, Smooth Brome does not. After blooming, the branches of Smooth Brome’s panicles often contract and then the whole seed head curves to the side. 

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field of smooth brome
Smooth Brome can be a problem in prairie restorations when it occurs in large patches.
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hand holding grass blade with a crimp
Look for a m-shaped crimp on the leaf blades of Smooth Brome.
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hand holding grass blade back from stem to show ligule
Smooth Brome has a short, membranous ligule.
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panicle inflorescence of smooth brome
Smooth Brome produces a panicle inflorescence with elongated spikelets.
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dried out inflorescence of smooth brome
As the season progresses and the grass senesces, the inflorescence droops strongly to one side. The whole grass takes on a grayish straw color.
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dried curled leaves of smooth brome
The leaves of Smooth Brome curl tightly when they dry and rustle in the wind.
How to Identify Smooth Brome

Smooth Brome, Bromus inermis, is a non-native, cool season grass found throughout Illinois. It grows between two and four feet tall, and it produces rather weak, broad leaves that have an m-shaped crimp across the blades, which you can feel if you run the blade between your fingers. It...