CPC National Collection Plant Profile

Poa atropurpurea

Chelsea Vollmer

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CPC National Collection Plant Profile

Poa atropurpurea

Common Name: 
San Bernardino Bluegrass
Growth Habit: 
CPC Number: 


Profile Links

 Forest Service

Poa atropurpureaenlarge
Photographer: Chelsea Vollmer
Image Owner: Rancho Santa Ana

Poa atropurpurea is Not Sponsored
Primary custodian for this plant in the CPC National Collection of Endangered Plants is: 
Sula Vanderplank contributed to this Plant Profile.
The initial writing of this profile was funded by the U.S. Forest Service

Poa atropurpurea

Poa atropurpurea (San Bernardino Bluegrass) is a member of the grass family (Poaceae) that is dioecious (separate male and female plants), growing as a tufted perennial with creeping rhizomes (Soreng 1993). This species is endemic to southern California and occurs in the Big Bear region of the San Bernardino Mountains, and in the Laguna and Palomar Mountains of San Diego County (CNDDB 2007). It often co-occurs with another endangered species Taraxacum californicum (California dandelion).

This species is differentiated from Kentucky bluegrass (Poa pratensis) by its shorter, narrower inflorescences, contracted panicles, and glabrous floral features (Soreng 1993). Poa atropurpurea panicles are purple while the flowers are open and flowers earlier in the year (Apr – June) than P. pratensis which often occurs at the same locations and it thought to hybridize with P. atropurpurea (USDA FS 2007). Poa atropurpurea is known from less than 20 location and was listed as Federally endangered in 1998. Critical habitat designations for this species were recently proposed (Eliason, 2007).

Distribution & Occurrence

State Range
State Range of  Poa atropurpurea
  Poa atropurpurea is restricted to wet montane meadows (Volgarino 2000) that are subject to flooding in wet years, described as “vernally wet marshlands” by Hirshberg (1994). This species is also found along the drier margins separate from more mesic plants such as P. pratensis, Carex spp., or Juncus spp. The perimeter of such meadows often intergrades with sagebrush scrub dominated by sagebrush or pine forest (Krantz 1981). Critical habitat assessment (Eliason 2007) has found two habitat parameters to be essential to this species: (1) Wet meadows subject to flooding during wet years at elevations of 6,000 to 8,100 feet (1,800 to 2,469 meters), that provide space for individual and population growth, reproduction, and dispersal; and (2) Well-drained, loamy alluvial to sandy loam soils occurring in the wet meadow system, with a 0 to 16 percent slope, to provide water, air, minerals, and other nutritional or physiological requirements to the species.

  Poa atropurpurea is endemic to southern California and occurs in only two counties (San Bernardino and San Diego). In San Bernardino County, Poa atropurpurea occurrences have been reported near Big Bear Lake in Bluff Meadow, Hitchcock Meadow, Belleville Meadow, North Shay Meadow, North Baldwin Lake Meadow, Cienega Seca Meadow, and Pan Hot Springs Meadow (SBNF 2000). In San Diego County, P. atropurpurea has also been reported from Mendenhall Valley on Palomar Mountain, Laguna Meadow on Laguna Mountain, and Bear Valley southwest of Laguna Mountain (CNDDB 2007). This species is known from fewer than 20 occurences throughout its range on Federal, State, and private lands in the San Bernardino, Laguna, and Palomar Mountains (FWS 1998).

Number Left
  According to survey information recorded in the California Natural Diversity Database, (CNDDB) 21 occurrences of Poa atropurpurea are currently known (CNDDB 2007). However, surveyor information submitted to the CNDDB comes from surveyors using various methods to record species occurrence information, therefore, the status and distribution of this species is considered in terms of the number of meadow areas currently occupied this species. The listing proposal (1998) cited less than 20 known occurrences. According to occurrence information from the SBNF (SBNF 2000; SBNF 2002) and the CNDDB (2007), P. atropurpurea has been documented in 15 meadow areas in the Big Bear area, and four meadow areas in the Laguna and Palomar mountains of San Diego. According to the final listing rule, population sizes of P. atropurpurea typically range from two to 300 individuals, although 3,000 individuals were reported from Belleville Meadow in 1999 (SBNF 2000).


Global Rank:  
Guide to Global Ranks
Federal Status:  
Guide to Federal Status
Recovery Plan:  

State/Area Protection
  State/Area Rank Status Date  
  California S2.2 CNPS 1B.2 12/31/2007  

Conservation, Ecology & Research

Ecological Relationships
  Taraxacum californicum, (California dandelion) is a thick rooted perennial herb in the sunflower family (Asteraceae) that often co-occurs with Poa atropurpurea in montane meadows in the Big Bear region of the San Bernardino Mountains (Krantz 1981) although T. californicum is known from almost twice as many localities (CNDDB 2007). Wind pollination, the need for male and female plants, and permanent water source/intact hydrology are all important for the survival of P. atropurpurea. Associated species recorded for this plant in the San Bernardino Mountains include: Iris missouriensis (rocky mountain Iris), Montia chamissoi (toad lily), Montiastrum lineare and Juncus xiphiodes (Iris-leaved rush) in the wetter areas, Layia platyglossa (tidy tips), Lasthenia californica (goldenfields) and Chaetopappa aurea in drier areas. Other associated species included Ranuncuculs californicus (California buttercup)and Sidalcea malvaeflora (checker mallow) (Hirschberg 1994).

  • Habitat Loss and degradation urban and recreational development
• Fragmentation from off-road vehicle traffic
• Grazing by livestock and feral burros (affecting seed consumption and exacerbating the invasion of non-native species).
• Hybridization with Kentucky bluegrass (Poa pratensis)
• Competition from invasive plants
• Population gender ratios:
Co-occurrence of male and female plants of Poa atropurpurea is necessary for seed production (FSW 1998). There is evidence that populations of P. atropurpurea in San Diego County are threatened by loss of genetic diversity and skewed sex ratios. According to the CNDDB (2007), all individuals reported from Bear Valley may be a single clone. Hirshberg (1994) reported only 4 males out of 1,140 total individuals during field surveys of Laguna Meadow, an overall 1:285 male to female ratio. All five herbarium specimens from Laguna Meadow reviewed by Curto (1992) were female (one from 1978, three from 1981, and one from 1991). It is not known what may be the cause of these skewed sex ratios, or how the sex ratios may vary annually.

Current Research Summary
  No herbarium specimens of male plants of Poa atropurpurea had been reported from the southern end of its range (San Diego County) until quite recently. During a study on the Cleveland National Forest (San Diego County) a total of just four male plants were discovered, two at each of two different populations (Hirshberg, 1994). It has been suggested that it is possible the San Diego County populations have turned apomictic (not needing fertilization). This would be evident by a seed set of 20 percent or higher (USDA FS 2007). Much more research is needed on the fertilization processes and natural history of this species

Current Management Summary
  Of the known Poa atropurpurea occurrences, 81 % are currently under claim for mining, or on private lands with limited protection (USDA FS 2007). An estimated 91% of meadow habitat has been eliminated since 1900, of the remaining land 70% of the meadows in the Big Bear area are currently without protection (FWS 1998). Two management guides are published by the US Forest Service, that address conservation of this species: the Cleveland National Forest habitat management guide for four sensitive plant species in mountain meadows; and the San Bernardino National Forest Meadow Habitat Management Guide.

There have already been proposals for the individual management of each occurrence and sometimes significant implementation of management practices to conserve Poa atropurpurea. Examples include seasonal cattle exclosures in Laguna Meadow (CNF 1991), and recreational trail closures in Belleville Meadow near Big Bear Lake (SBNF 2002a). Burro removal in the San Bernardino National forest has also been effected after livestock were seen grazing in P. atropurpurea meadows (USDA FS 2007).

It should be noted that habitat management guides and plans are voluntary guidelines and do not provide protection or long-term conservation of the species on US Forest Service lands. A recovery plan for this species is being developed but is not yet complete (USDA FS 2007). Some recommended practices include monitoring fence lines (repairing as necessary), continuing to survey for Poa atropurpurea on NFS lands and visiting populations to update information on populations that have not been visited for ten years of more (USDA FS 2007).

Research Management Needs
  Sound management practices in the National Forest lands will be crucial to the recovery of this species, through protection of known populations, habitat restoration, acquisition of lands that support other occurrences, plus additional monitoring and research to guide future management practices (USDA FS 2007) Poa atropurpurea needs non-compacted, non-eroded soils, a perennial water source, relatively intact meadow systems and limited invasion of exotic species for its reproduction, growth and survival (Curto 1997; Eliason 2007). In order to maintain wet meadows and forest openings to enable the survival of this species invasive and exotic species will need to be monitored and controlled as appropriate.

A population level study to assess genetic diversity throughout the range of this species would provide a basis for determining future management descisions. For the genetic diversity of this species it may be necessary to encourage seed set through special management considerations (Eliason 2007). Protection and possibly propagation of male P. atropurpurea plants may be required to maintain P. atropurpurea populations in the future (Eliason 2007). Seed set in plants at the southern end of the range should be investigated to assess apomictic (clonal seed) reproduction. A genetic study to assess whether hybridization between Poa atropurpurea and P. pratensis is occurring, and to what extent, would also help to elucidate the genetic status of this species.

Monitoring Efforts
  In San Bernardino National Forest a large amount of meadow habitat (430 ac (1,793 ha)) has been mapped and monitoring efforts for this species and its potential habitat are ongoing. A recovery plan is being developed and a critical habitat proposal in progress. The initiation of 5-yr reviews began in 2006.

Ex Situ Needs
  •A common greenhouse study to look at factors that might affect reproduction and the sex ratio of seedlings.

•An assessment of whether introducing more male plants to populations with skewed sex ratios would improve cross-fertilization and support population survival.

•Development of a seedbank for future reintroduction and restoration efforts.


Books (Single Authors)

Munz, P.A. 1974. A flora of southern California. Berkeley: Univ. California Press. 1086p.

Books (Edited Volumes)

The Jepson manual: higher plants of California. In: Hickman, J. C., editor. University of California Press. p 1400.

Electronic Sources

California Native Plant Society. (2007). Inventory of rare and endangered plants. [online database].v7-07d http://cnps.org/inventory. Accessed: 2007.

California Natural Diversity Database [CNDDB]. (2007). Rarefind. [Database].Version 3.1.1 (Dec 2007) http://www.dfg.ca.gov/biogeodata/. Accessed: 2007.

USDA Forest Service [USDA FS]. (2007). Species Accounts –Plants. [pdf].1 http://www.fs.fed.us/r5/scfpr/projects/lmp/docs/species-plants.pdf. Accessed: 2007.

Journal Articles

Marsh, V.L. 1952. A Taxonomic Revision of the Genus Poa of United States and Southern Canada. American Midland Naturalist. 47: 202-250.

Soreng, R.J. 1991. Systematics of the "Epiles" Group of Poa (Poaceae). Systematic Botany. 16: 507-52.

Soreng, R.J. 1998. An Infrageneric Classification for Poa in North America, and Other Notes on Sections, Species, and Subspecies of Poa, Puccinellia, and Dissanthelium (Poaceae). Novon. 8: 187-202.

United States Fish and Wildlife Service [USFWS]. 1998. U.S. Fish and Wildlife Service. Endangered and threatened wildlife and plants; final rule to determine endangered or threatened status for six plants from the mountains of southern California. Federal Register. 63: 49006-49022.


Anderson, A. 2007. Notes and Summary of Poa atropurpurea Surveys in Mendenhall Valley 5/3/2007. Carslbad, CA. Carlsbad Fish and Wildlife Office.

CNF (Cleveland National Forest). 1991. Habitat Management Guide for the Sensitive Plant Species: Delphinium hesperium ssp. cuyamacae, Lilium parryi, Limnanthes gracilis var. parishii, Poa atropurpurea In Riparian Montane Meadows. San Diego, CA. CNF (Cleveland National Forest).

Curto, M. 1992. Status of San Bernardino bluegrass within the Cleveland National Forest. San Louis Obispo, CA. R.F. Hoover Herbarium, California Polytechnic State University.

Denslow, M.; Fraga, N.; Gross, L.; Maurice, A.; Sanbui, S.; Soza, V; Tessel, S. 2002. 2002 Meadow Surveys: San Bernardino National Forest. Claremont. Rancho Santa Ana Botanic Garden.

SBNF (San Bernardino National Forest). 2002. Meadows Habitat Management Guide. Fawnskin, CA. San Bernardino National Forest.

Volgarino, D.; Butler, R.; Lardner, M.; Winter, K. 2000. Criteria for Modeled Habitat Poa atropurpurea (San Bernardino bluegrass). San Bernardino, CA. San Bernardino National Forest.


Krantz, T.P. 1994. A Phytogeography of the San Bernardino Mountains, San Bernardino County, California. [PhD dissertation]: University of California at Berkeley. Berkeley .

  This profile was updated on 3/4/2010
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