The following Participating Institutions are custodians for this species in the CPC National Collection:
Rancho Santa Ana Botanic Garden
The conservation of Poa atropurpurea is fully sponsored.
Sula Vanderplank contributed to this Plant Profile.
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
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.
|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).|
Conservation, Ecology & Research
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 K
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).
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.
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.
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.