North America Non-native Plant

Smooth Barley

Botanical name: Hordeum murinum glaucum

USDA symbol: HOMUG

Life cycle: annual

Habit: grass

Native status: A waif, a non-native that isn't naturalized in Canada ⚘ Non-native, reproduces and persists in the wild in the lower 48 states  

Synonyms: Critesion glaucum (Steud.) Á. Löve (CRGL13)  ⚘  Critesion murinum (L.) Á. Löve ssp. glaucum (Steud.) W.A. Weber (CRMUG)  ⚘  Hordeum glaucum Steud. (HOGL)  ⚘  Hordeum stebbinsii Covas (HOST)   

Smooth Barley: Understanding This Non-Native Annual Grass If you’ve ever wondered about that persistent grass popping up in disturbed areas around your property, you might be looking at smooth barley (Hordeum murinum glaucum). This annual grass has quite the story to tell, and whether you’re dealing with it in your ...

Smooth Barley: Understanding This Non-Native Annual Grass

If you’ve ever wondered about that persistent grass popping up in disturbed areas around your property, you might be looking at smooth barley (Hordeum murinum glaucum). This annual grass has quite the story to tell, and whether you’re dealing with it in your landscape or considering it for a specific purpose, it’s worth understanding what you’re working with.

What is Smooth Barley?

Smooth barley belongs to the same family as our familiar lawn grasses and cereal grains – the Poaceae family. As its botanical name Hordeum murinum glaucum suggests, it’s related to cultivated barley, though this wild cousin has taken a very different path. You might also see it referenced under several scientific synonyms, including Critesion glaucum or Hordeum glaucum, depending on which botanical reference you’re consulting.

This annual grass completes its entire life cycle in one growing season, making it a quick colonizer of available space. Its grass-like appearance fits right into the broader category of graminoids – those grass-like plants that include true grasses, sedges, and rushes.

Where You’ll Find Smooth Barley

Originally hailing from regions outside North America, smooth barley has made itself at home across a wide swath of the continent. You can encounter it from coast to coast, including Alberta and British Columbia in Canada, and throughout numerous U.S. states including Alabama, Arizona, California, Colorado, Idaho, Nevada, New Mexico, Oklahoma, Oregon, Texas, Utah, and Washington.

In Canada, it’s considered a waif – essentially a plant that shows up temporarily but doesn’t stick around permanently. However, in the lower 48 states, it has established itself more successfully, reproducing on its own and persisting in the landscape without human assistance.

Should You Plant Smooth Barley?

Here’s where things get interesting. While smooth barley isn’t typically considered a garden ornamental, understanding its role can help you make informed decisions about your landscape.

Reasons You Might Consider It:

  • Extremely low maintenance once established
  • Drought tolerant and adaptable to various growing conditions
  • Quick to establish in disturbed soils
  • Can provide temporary ground cover

Reasons You Might Want to Skip It:

  • Limited ornamental value compared to native alternatives
  • As a non-native species, it doesn’t support local ecosystems as effectively
  • Can be weedy in appearance
  • May compete with more desirable native plants

Growing Conditions and Care

If smooth barley does end up in your landscape (whether by choice or chance), it’s remarkably unfussy. This adaptable grass thrives in a wide range of USDA hardiness zones and growing conditions. It’s particularly well-suited to areas with poor soil and limited water availability.

As an annual, it will complete its growing cycle within one season, typically germinating in spring, growing through summer, and setting seed before dying back in fall or winter.

Better Native Alternatives

If you’re looking for native grasses that can provide similar benefits while supporting local wildlife and ecosystems, consider these alternatives based on your region:

  • Native fescues and bunchgrasses for western regions
  • Little bluestem or buffalo grass for prairie areas
  • Regional native sedges for areas with variable moisture

These native alternatives will provide better wildlife habitat, support pollinators and other beneficial insects, and contribute to the local ecological web in ways that non-native species simply cannot.

The Bottom Line

Smooth barley represents one of those plants that exists in the gray area between useful and weedy. While it’s not inherently harmful, it’s also not contributing as much to your local ecosystem as native alternatives could. If you encounter it in your landscape, you can let it be without major concern, but for intentional plantings, native grasses will give you more ecological bang for your buck.

Understanding plants like smooth barley helps us make better decisions about creating landscapes that are both functional and supportive of local wildlife. After all, every plant choice is an opportunity to either support or miss supporting the intricate web of life in our own backyards.

Smooth Barley

Classification

Group

Monocot

Kingdom

Plantae - Plants

Subkingdom

Tracheobionta - Vascular plants

Superdivision

Spermatophyta - Seed plants

Division

Magnoliophyta - Flowering plants

Subdivision
Class

Liliopsida - Monocotyledons

Subclass

Commelinidae

Order

Cyperales

Family

Poaceae Barnhart - Grass family

Genus

Hordeum L. - barley

Species

Hordeum murinum L. - mouse barley

Plant data source: USDA, NRCS 2025. The PLANTS Database. https://plants.usda.gov,. 2/25/2025. National Plant Data Team, Greensboro, NC USA