Palomar Monkeyflower [Mimulus diffusus Grant]

Palomar Monkeyflower [Mimulus diffusus Grant]

Listing CNPS List 4 R-E-D Code 1-1-1

State/Federal. Status -- None SCROPHULARIACEAE Apr.-Jun.

Global Rank G3G5Q State Rank S?

Distribution: San Diego County, Orange County, and Riverside County; Baja California, Mexico; also outside Southern California in the Sierra Nevada foothills, the Tehachapi Mountains, western Mohave, and outer South Coast Ranges

Habitat: Lower Montane Coniferous Forest and Chaparral understory are typically utilized by this small but colorful annual. Near Warner's Hot Springs this plant was flowering on the partially shaded, moist embankments of Agua Caliente Creek in a riparian woodland; south of Green Valley Campground it was found in xeric openings in the Chamise dominated chaparral. At Shrine Camp it occurred beneath conifers near very mesic meadows. These very different habitats may indicate some genetic variation occurs within these populations, or that it can tolerate a wide variety of microhabitats. Soil types utilized include Reiff fine sandy loam at Shrine Camp, and Tujunga Sand at Agua Caliente Creek.

Known Sites: Palomar Monkeyflower is occasional in ecotonal chaparral/Jeffrey Pine habitat near the southern entrance to Cuyamaca Rancho State Park. It is rare at Shrine Camp in the meadow; one vigorous colony occurs near Descanso north of Merrigan Ranch. It is found along Agua Caliente Creek in wet sand near Warner's Hot Springs. Also reported from scattered San Diego County locales that include Santa Ysabel/Witch Creek, Boulder Creek, Pine Valley, and McCain Valley. Herbarium specimens at the San Diego Natural History Museum are from Lost Valley near Los Coyotes Indian Reservation, Lark Canyon Near Live Oak Spring, Morena Lake, Corte Madera, a meadow at the foot of Morgan Hill in the Palomar Mountains, at Echo Dell, a burn between Campo and Canyon City, at the Silverwood Wildlife Sanctuary near Barona, Airplane Ridge in the Cuyamaca Mountains, the hills above Lake Wohlford, Tecate Mountain, and at Oakcrest Park in Encinitas. Specimens in nearby Riverside County are from Kenworthy Station in Garner Valley and near Santa Rosa Mountain Road. This species grows in a xeric chaparral at lower elevations in western Riverside County near the intersection of Colt Road and De Portola Road; also to the south near Calle Azur and Glen Oak Valley Road, and just east of the Dripping Springs Ranger Station. An old biological survey report notes this species on a hillside west of the Laurel Cemetery on Mesa de Burro of the Santa Rosa Plateau. It is reported by Roberts for the vicinity of Trabuco Peak, Orange County.

Eighteen specimens from Baja California are found in the herbarium of the San Diego Natural History Museum south to 31 41' North where collected by Moran (SD 83849) 2 miles south of Rancho Tres Hermanos.

Status: Palomar Monkeyflower is slowly declining in Southern California. Increased recreational activity (i.e., camping, hiking) in the mountains is likely to further impact known populations. Substantial portions of all sizeable populations should be protected. The populations mentioned herein are listed in synonymy with Mimulus palmeri in the 1993 Jepson Manual under the David Thompson treatment; however, Mimulus diffusus is being retained as a distinctive species in the CNPS listings pending additional taxonomic research.

Copyright May 1994 Craig H. Reiser.

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