Smooth brome grass (Bromus inermis)

patch of spotted knapweed plants with pink/purple flowers

 
 

Smooth brome is a grass that is commonly found in Minnesota in sunny areas. It was widely planted for forage and erosion control. Smooth brome emerges early in the season and forms dense cover in grasslands, roadsides, ditches, and moist wooded areas.

Description

Appearance

Smooth brome is a perennial cool season grass. It grows 2-4 feet high, with a hairless stem.

Leaves and Stem

The leaf blade is about ¼ inch wide. The leaves have an "M"- or "W"-shaped constriction. Leaves alternate in coming off the stem and are usually hairless.

Flowers

Smooth brome has a loose branching cluster of flowers (open panicle). Flowers bloom in June and July. The anthers are yellow and hang down from the flowers.

Seeds

The seeds are brown, flat, and oblong. Smooth brome can spread vegetatively by underground stems called rhizomes.

Rhizomes and Roots

Smooth brome reproduces vegetatively through horizontal stems growing below the soil surface, called rhizomes. Rhizomes form roots and produce new plants.

Biology

Smooth brome is a perennial grass. It can grow 2-4 feet tall. It reproduces both sexually via seeds and vegetatively by underground rhizomes. It is tolerant of a wide variety of conditions, but prefers moist soils and sunny locations.

Origin and Spread

Smooth brome is native to Europe and Asia. It was imported in the late 1800s and was widely used as a forage grass, for hay production, and for erosion control. It is found throughout Minnesota.

Refer to EDDMapS Distribution Maps for current distribution.

Don't be fooled by these look-alikes

  • Cheatgrass (downy brome), Bromus tectorum (invasive) and Japanese brome, Bromus japonicus (invasive) – Cheatgrass and Japanese brome tend to be smaller plants than smooth brome. Their seeds have an awn (hair-like bristle) at their tip. Both are annuals.
  • Hairy woodland brome, Bromus pubescens (native) – Minnesota has several native Bromus species. Hairy woodland brome is covered in fine hairs. (No image)
  • Reed canarygrass, Phalaris arundinacea (invasive) - Reed canarygrass seedheads are not as branched as smooth brome.  Reed canarygrass leaves have a membrane where they attach to the stem and do not have the "M"-shaped crinkle of smooth brome.
 
Regulatory Classification

Smooth brome is not regulated.

Threat to Minnesota

It can form dense cover and outcompete other species. It spreads into grasslands, prairies, roadsides, ditches, and moist wooded areas. It starts growing early in the spring before native warm season grasses.

What you should do

One way that invasive plant seeds and fragments can spread is in soil. Sometimes plants are planted purposefully. You can prevent the spread of invasive plants.

PlayCleanGo: Stop Invasive Species in Your Tracks

  • REMOVE plants, animals & mud from boots, gear, pets & vehicle.
  • CLEAN your gear before entering & leaving the recreation site.
  • STAY on designated roads & trails.
  • PLANT non-invasive species.
Native Substitutes
 
Control Methods

Mechanical control can reduce smooth brome. Mowing in the spring should be followed up by additional mowing as needed. Late spring burns can reduce smooth brome.

Herbicide can be used when mowing and then, after a flush of growth, followed up with spraying repeatedly with glyphosate as needed.

Reporting
  • This species is unregulated, but you can add to the public information about this species by reporting new occurrences through EDDMapS Midwest.
Resources