A recent report comes from the south side of Lower Otay Lake. Herbarium collections at San Diego's Museum of Natural History include specimens collected south of Poway Grade, on Point Loma above Loma Portal, the southeast end of Lee Valley, at Lake Murray, the northeastern slope of El Cajon Mountain, Camp Kearny, Mount Soledad, a hill west of Felicita Park, and near the corner of Balour and Encinitas Drive in Encinitas. Old biological survey reports note sites near Sundance Avenue and Carmel Mountain Road, west of Valley Center Road and south of Banbury Drive, in Carroll Canyon east of El Camino Memorial Park, a west facing slope above Honey Springs Road on Honey Springs Ranch, on Goat Peak north of Beeler Canyon in Poway, on the east slope of Bottle Peak near Lake Wohlford, and on the east side of Genesee Avenue and bounded by Miramar Road and La Jolla Village Drive and Regents Road. Reported by Roberts from Orange County at Temple Hill in Blue Bird Canyon near Laguna Beach. California Adder's Tongue Fern is declining in San Diego County.
Populations are typically quite small and growth is triggered by the slightest rainfall.
As a result, this cryptic species is often difficult to find at known sites during extended periods without rainfall. Censusing for this fern is best done only following recent substantial rainfall. Given its apparent rarity in Southern California, substantial portions of sizeable populations are recommended for protection. Copyright May 1994 Craig H. Reiser.