Hordeum murinum - L.
Mouse Barley
Other Common Names: mouse barley
Taxonomic Status: Accepted
Related ITIS Name(s): Hordeum murinum L. (TSN 40881)
French Common Names: orge des rats
Unique Identifier: ELEMENT_GLOBAL.2.133559
Element Code: PMPOA380A0
Informal Taxonomy: Plants, Vascular - Flowering Plants - Grass Family
 
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Monocotyledoneae Cyperales Poaceae Hordeum
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Concept Reference
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Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Hordeum murinum
Conservation Status
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NatureServe Status

Global Status: GNR
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (26Apr2016)

U.S. & Canada State/Province Status
United States Alabama (SNA), Arizona (SNA), California (SNA), Colorado (SNR), Connecticut (SNA), Delaware (SNA), District of Columbia (SNR), Georgia (SNR), Hawaii (SNA), Idaho (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNR), Montana (SNA), Nevada (SNA), New Jersey (SNA), New Mexico (SNA), New York (SNA), North Carolina (SNA), Oklahoma (SNA), Oregon (SNA), Pennsylvania (SNA), Texas (SNA), Utah (SNA), Virginia (SNA), Washington (SNA), Wyoming (SNA)
Canada Alberta (SNR), British Columbia (SNR)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

Distribution
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U.S. States and Canadian Provinces
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States ALexotic, AZexotic, CAexotic, CO, CTexotic, DC, DEexotic, GA, HIexotic, IDexotic, MA, MDexotic, MEexotic, MTexotic, NCexotic, NJexotic, NMexotic, NVexotic, NYexotic, OKexotic, ORexotic, PAexotic, TXexotic, UTexotic, VAexotic, WAexotic, WYexotic
Canada AB, BC

Range Map
No map available.

Ecology & Life History Not yet assessed
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Economic Attributes Not yet assessed
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Management Summary Not yet assessed
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Population/Occurrence Delineation Not yet assessed
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Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank)
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Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High/Low
Rounded I-Rank: Unknown
I-Rank Reasons Summary: Hordeum murinum is naturalized in the western and the eastern U.S. It is especially competitive to native annuals in arid areas in the western U.S. Hordeum murinum forms dense swards that displace native grasses and forbs. In the western U.S., it occurs in mesquite bosques, grasslands of California's Central Valley and Coast Ranges, and is widely distributed in the Sonoran Floristic Province. Hordeum murinum is disturbance-adapted and occurs where land has been disturbed, especially areas that have been grazed. The seeds easily disperse when the long awn attaches to animals. More information is needed especially about negative impacts in its range, trends and management difficulty.
Subrank I - Ecological Impact: Medium/Low
Subrank II - Current Distribution/Abundance: High/Medium
Subrank III - Trend in Distribution/Abundance: High/Low
Subrank IV - Management Difficulty: Medium/Insignificant
I-Rank Review Date: 01Mar2004
Evaluator: Tomaino, A.
Native anywhere in the U.S?
Native Range: Native to to Europe, north Africa, and tropical Asia (Weber 2003).

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Established outside cultivation in the U.S. (Kartesz 1999).

S-2. Present in conservation areas or other native species habitat? Yes
Comments: An invasive exotic in natural areas in the western U.S. (Weber 2003).

Subrank I - Ecological Impact: Medium/Low

1. Impact on Ecosystem Processes and System-wide Parameters:Medium significance/Insignificant
Comments: Does not have any characters that suggest it would severely alter ecosystem processes.

2. Impact on Ecological Community Structure:Moderate significance
Comments: It forms dense swards that displace native grasses and forbs (Weber 2003). It often carpets the spring understory of mesquite woodlands where native competition has been diminished by intensive grazing (Tellman 2002). In 1951, it was described as the most common barley in California ranges, being especially abundant in valleys and foothillls where it frequently formed pure stands (Sampson et al. in Dean 1990). Hordeum murinum germinates after winter/spring rains, but has less specific germination requirements that natives; this allows it to establish earlier and dominate the forest floor before other species have a chance (Beatley 1974, Davison 1971, in Tellman 2002).

3. Impact on Ecological Community Composition:High/Moderate significance
Comments: It forms dense swards that displace native grasses and forbs by competing for water, nutrients and space (Weber 2003). The grass is highly competitve to native annuals in arid areas. It often carpets the spring understory of mesquite woodlands where native competition has been diminished by intensive grazing (Tellman 2002). In 1951, it was described as the most common barley in California ranges, being especially abundant in valleys and foothillls where it frequently formed pure stands (Sampson et al. in Dean 1990).

4. Impact on Individual Native Plant or Animal Species:Unknown

5. Conservation Significance of the Communities and Native Species Threatened:Medium/Low significance
Comments: In Arizona, it is a common understory plant in mesquite bosques of Arizona's Hassayampa River (Richter 1990 in Dean 1990). It grows on well-drained soils and sometimes on clay in grasslands of California's Central Valley and coastal ranges (Briggs 1990 in Dean 1990). Hordeum murinum is the 8th or 9th most widely distributed species in the exotic flora of the Sonoran Floristic Province (Tellman 2002). Presumeably at least some communities or species are of conservation significance in this region. However, Hordeum murinum seems to usually occur in disturbed areas. It is a successful invader in Mediterranean climates where land has been disturbed (Dean 1990).

Subrank II. Current Distribution and Abundance: High/Medium

6. Current Range Size in Nation:High significance
Comments: In the western U.S., occurs from Montana south to Texas and west (Kartesz 1999). In the eastern U.S., occurs in Maine, Massachusetts, and New York south to Alabama (Kartesz 1999). Also occurs in Hawaii (Kartesz 1999).

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Medium/Low significance
Comments: Hordeum murinum is highly competitive to native annuals in arid areas. In the eastern U.S., it occurs sporadically in waste places (Gleason and Cronquist 1991). It is the 8th or 9th most widely distributed species in the exotic flora of the Sonoran Floristic Province (Tellman 2002). It grows most often on well-drained soils and sometimes on clay in grasslands of California's Central Valley and coastal ranges (Briggs 1990 in Dean 1990).

8. Proportion of Nation's Biogeographic Units Invaded:High/Moderate significance
Comments: At most 87% of units. At least 14% of units, inferred from Kartesz (1999) and TNC (2001).

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Medium/Low significance
Comments: In Arizona, it is a common understory plant in mesquite bosques of Arizona's Hassayampa River (Richter 1990 in Dean 1990). In 1951, it was described as the most common barley in California ranges, being especially abundant in valleys and foothillls where it frequently formed pure stands (Sampson et al. in Dean 1990). It grows most often on well-drained soils and sometimes on clay in grasslands of California's Central Valley and coastal ranges (Briggs 1990 in Dean 1990). Hordeum murinum is the 8th or 9th most widely distributed species in the exotic flora of the Sonoran Floristic Province (Tellman 2002).

Subrank III. Trend in Distribution and Abundance: High/Low

10. Current Trend in Total Range within Nation:High/Low significance
Comments: Found in disturbed areas. Disturbed areas are not declinng, therefore it is presumed to not be declining. In California, found in moist, generally disturbed sites (Baldwin et al. 2004).

11. Proportion of Potential Range Currently Occupied:Low significance
Comments: Inferred from USDA (1990) and Kartesz (1999), 30-90% of its potential range in the U.S. is currently occupied.

12. Long-distance Dispersal Potential within Nation:High/Moderate significance
Comments: The seeds easily disperse when the long awn attaches to stock and wildlife and then to the soil (Dean 1990).

13. Local Range Expansion or Change in Abundance:High/Low significance
Comments: Found in disturbed areas. Disturbed areas are not declinng, therefore it is presumed to not be declining. In California, found in moist, generally disturbed sites (Baldwin et al. 2004).

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Low significance
Comments: In areas that are grazed, Hordeum murinum typically outcompetes the native annuals as well as the perennial grasses, forbes, and vines (Tellman 2002). It is a disturbace-adapted ruderal (Beatley 1966 in Tellman 2002). In California, it is found in moist, generally disturbed sites (Baldwin et al. 2004). In the eastern U.S., it occurs sporadically in waste places (Gleason and Cronquist 1991).

15. Similar Habitats Invaded Elsewhere:Medium/Low significance
Comments: In Australia, it is ubiquitous in pastures and is often found in dry temperate grasslands, semi-arid shrub woodlands, and eucalyptus shrublands (Dean 1990). It is known as an escape outside the region of interest. These habitats seem similar to ones it has already invaded in the region of interest.

16. Reproductive Characteristics:Moderate significance
Comments: Hordeum murinum germinates after winter/spring rains, but has less specific germination requirements that natives; this allows it to establish earlier and dominate the forest floor before other species have a chance (Beatley 1974, Davison 1971, in Tellman 2002). Annual life spans, rapid growth rates, and high reproductive efforts allow exotic ruderals such as Hordeum murinum to fare well in disturbed habitats such as those repeatedly grazed by domestic livestock, while defenses including stiff awns protect the seeds from being eaten (Brooks 1995, Mack 1986 in Tellman 2002). A small proportion of seed remains dormant but viable through the first growing season (Dean 1990). Hordeum murinum reaches maturity prior to dry summer conditions (Dean 1990). Research on the relationship between grazing and growth of Hordeum murinum in Australia is sometimes conflicting but indicates that it can resprout readily when grazed (Dean 1990).

Subrank IV. General Management Difficulty: Medium/Insignificant

17. General Management Difficulty:High/Low significance
Comments: Some herbicides have proven effective in controlling it in agricultural fields (Dean 1990). In California, mowing was found to have only an immediate effect, with the grass returning the following year (Dean 1990). Little research has apparently been conducted on Hordeum leporinum in natural areas in the U.S. (Dean 1990). In Australia some degree of control was achieved by a mowing and native plant reseeding program; the treatment was most effective when repeated for one or two years (Dean 1990).

18. Minimum Time Commitment:Low significance/Insignificant
Comments: It is an annual (Weber 2003). Little information is available on its control in the U.S. However, in Australia some degree of control was achieved by a mowing and native plant reseeding program; the treatment was most effective when repeated for one or two years (Dean 1990).

19. Impacts of Management on Native Species:Medium significance/Insignificant
Comments: Since hand-pulling (Weber 2003) and mowing (Dean 1990) are options, it would not be the case that the only effective methods for managing this species would cause persistent reductions in the abundance of native species.

20. Accessibility of Invaded Areas:Medium significance/Insignificant
Comments: Although it is high quality forage early in the growing season, as the plant matures it is damaging to stock animals; the awns on the seed penetrate eyes and skin and damage wool (Warr 1981 in Dean 1990). Therefore, it would seem likely that at least some landowners would welcome it's control.
Authors/Contributors
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Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

References
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  • Baldwin, B.G., S. Boyd, B.J. Ertter, D.J. Keil, R.W. Patterson, T.J. Rosatti and D.H. Wilken. 2004.
    Jepson Flora Project, Jepson Online Interchange for California Floristics. Regents of the University of California, Berkeley. Online. Available: http://ucjeps.berkeley.edu/jepson_flora_project.html (Accessed 2004).

  • Dean, S. A. 1990. Element Stewardship Abstract for Hordeum murinum ssp. leporinum. The Nature Conservancy. 20 pp. Online. Available: http://tncweeds.ucdavis.edu/esadocs/hordmur1.html (accessed 2004).

  • Flora of North America Editorial Committee. 2007a. Flora of North America North of Mexico. Vol. 24. Magnoliophyta: Commelinidae (in part): Poaceae, part 1. Oxford Univ. Press, New York. xxviii + 911 pp.

  • Gleason, H.A., and A. Cronquist. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. New York Botanical Garden, Bronx, New York. 910 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Tellman, B., editor. 2002. Invasive Exotic Species in the Sonoran Region. The University of Arizona Press and the Arizona-Sonora Desert Museum, Tucson. 424 pp.

  • The Nature Conservancy. 2001. Map: TNC Ecoregions of the United States. Modification of Bailey Ecoregions. Online . Accessed May 2003.

  • USDA Agricultural Research Service. 1990. USDA Plants Hardiness Zone Map. Misc. Publ. Number 1475.

  • Weber, E. 2003. Invasive plant species of the world: a reference guide to environmental weeds. CABI Publishing, Cambridge, Massachusetts. 548 pp.

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