Family: Poaceae

Origin, Description & Uses:
Muhlenbergia rigens (deer grass) is a perennial bunchgrass native to the southwestern and south-central United States and extending into Mexico. It is well known for its large, fountain-like clumps of narrow, arching green leaves and its tall, airy flower spikes that turn golden-tan as they mature. This ornamental grass is widely valued in landscaping for its drought tolerance, low maintenance needs, and striking visual texture in gardens, parks, and restoration plantings. It has also been traditionally used in some regions for weaving and basketry, and it can provide habitat and cover for wildlife in its native range.

Risks & Threats:
While Muhlenbergia rigens is not currently known to be naturalized in the Hawaiian Islands, it possesses traits that are cause for concern. Its strong drought tolerance, ability to form dense clumps, and prolific seed production could allow it to establish and persist in dry to mesic habitats if introduced, potentially competing with native vegetation and altering plant community structure. As a large bunchgrass, it may also contribute to increased fine fuel loads, potentially influencing fire behavior in ecosystems where wildfire is not a natural or frequent disturbance. Because of these characteristics, it could detrimentally impact tropical island ecosystems if it were to become established. When possible, it is recommended to choose low risk or native alternatives that provide similar landscape or ecological functions without the associated invasion concerns.

High Risk Traits:

• Tolerates a wide range of climates and elevations (environmentally versatile)
  
• Can survive in subtropical climates
  
• Other Muhlenbergia species are documented to be invasive weeds
  
• Tolerates many soil conditions (and potentially able to exploit many different habitat types)
  
• Tolerates fire and could increase fire risks
  
• Can form almost pure ground cover in native range (could exclude other species)
  
• Reproduces by seeds and vegetatively via rhizomes
  
• Seeds likely dispersed by water, and possibly wind

Low Risk Traits:

• No records of naturalization outside widespread native range
  
• Evidence of weediness unconfirmed
  
• Non-toxic and palatable to grazing animals when young
  
• Landscaping and ornamental value
  
• Ethnobotanical uses (baskets, corn meal) for Native Americans
  
• Genus Muhlenbergia susceptible to herbicides