San Bernardino Blue Grass [Poa atropurpurea Scribn.]

San Bernardino Blue Grass [Poa atropurpurea Scribn.]

Listing CNPS List 1B R-E-D Code 2-2-3

State/Federal. Status -- /C1 POACEAE Apr.-Jun.

Global Rank G2 State Rank S2.2

Distribution: San Diego County, Riverside County, and San Bernardino County

Habitat: Montane Meadows surrounded by coniferous forest are the preferred habitat of this rhizomatous perennial grass. According to Krantz, it blooms earlier than other Poa species. At Laguna Lakes the soil type is mapped as loamy alluvial land. These meadows have been heavily grazed and now have a mix of native annuals and herbaceous perennials, with substantial Eurasian grasses. Small rocky areas within meadows may be a preferred microhabitat.

Known Sites: San Bernardino Blue Grass is growing in meadows near Big Laguna Lake sympatrically with Poa pratensis. Data Base reports here are on the north side of Los Rasalies Ravine, and in nearby Filaree Flats. Four locales within the meadow have been mapped; however, recent efforts to confirm these sightings have not been successful. Old reports are from nearby Crouch Meadow and at Mendenhall Valley in the Palomar Mountains. It is also reported north of San Diego County at Big Bear Lake by Eagle Point, and nearby at Bluff Lake in the San Bernardino Mountains. Data Base reports for San Bernardino County are from the north shore of Baldwin Lake, the south shore of Big Bear Lake between Eagle Point and Stanfield Cutoff, about 1.5 miles east of Holcomb Valley, in Holcomb Valley, in Cienaga Seca 1 mile southwest of Onyx Peak, at the eastern edge of Bluff Lake, just south of Meadow Park in the town of Big Bear Lake, the Presbyterian Conference grounds west to the south shore of Metcalf Bay, the Pan Hot Springs area of Big Bear City, Shay Meadow near the southeastern end of Big Bear Boulevard in Big Bear City, between Aeroplane Lane and Big Bear City Airport, at Moonridge near the golf course and ski areas, at Wildhorse Spring 3.4 miles southeast of Woodlands, Erwin Lake just east of Woodlands at the end of Meadow Lane, and at the east end of Erwin Lake about 1 mile east of Woodlands.

Status: This grass is presumed to be slowly declining in the San Bernardino Mountains due to residential development in areas of montane meadows. More information is needed regarding the status of this grass in San Diego County. Questions arise concerning the taxonomic integrity of this species in the Laguna Mountains. It may be getting "swamped" genetically by the very common Poa pratensis which apparently includes both native and introduced strains. Overgrazing by cattle has severely degraded the Laguna meadows and undoubtedly led to the extirpation of most of the historical population. Removal of grazing cattle from the Laguna Meadows is needed to protect not only this species but a number of uncommon or sensitive plants (e.g., Horkelia bolanderi ssp. clevelandii which is the uncommon host plant of the rare Laguna Mountains Skipper (Pyrgus ruralis lagunae). All populations of this grass in San Diego County should be protected.

Copyright May 1994 Craig H. Reiser.

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