Spreading [Navarretia fossalis Moran]
Listing CNPS List 1B R-E-D Code 2-3-2
State/Federal. Status -- /C1 POLEMONIACEAE Apr.-Jun.
Global Rank G2 State Rank S2.1
Distribution: Riverside County, San Diego County; Baja California, Mexico
Habitat: Vernal Pools and vernal swales are the preferred habitat of this small annual. Population size is strongly correlated with rainfall; during drought years plant numbers may be drastically reduced. Typically Psilocarphus brevissimus grows with Spreading Navarretia. Depth of pool appears to be a significant factor as this annual is rarely found in the shallow pools. Huerhuero loam is mapped for both the Dillon Road population and the vernal pool complex on Stewart Mesa at Camp Pendleton.
Known Sites: A vigorous population grows in the "J" series of vernal pools near Dillon Road on Otay Mesa. A particularly outstanding, well preserved pool has recently been protected as a mitigation site, and has been fenced. Orcuttia californica is common in this pool. Navarretia fossalis also grows in conspicuous mounded pools on La Media Road in an area which will probably soon be graded. A small colony occurs in a minor vernal swale near the northern terminus of Dillon Road. It is common in the single, large vernal pool just north of Mass 3 Road on Camp Pendleton. Spreading Navarretia also grows in the vast vernal pool near the Ramona Airport; the population is reported to fluctuate dramatically from year to year based on winter and spring rainfall. The small populations reported in downtown Ramona along Main Street are scheduled for imminent development. It is possibly still extant at the highly degraded vernal pool system in San Marcos east of Pacific Street, but could not be relocated in early spring, 1989. This locale appears to have been leveled recently by construction of Highway 52. Outstanding vernal pools around the Tijuana Airport immediately south of the border, which contain N. fossalis, probably are no longer extant owing to a bi-national effort to develop Otay Mesa. An old biological survey report notes this species southwest of Day Street in Ramona. Data Base reports for San Diego County note sites just south of Otay Mesa Road at the east end of Moody Canyon, both north and northwest of Brown Field, northeast of Montgomery Field between the runways and the fence, the vicinity of Highway 163 and Kearney Villa Road, a mesa at the head of Deer Canyon in Peñasquitos North, north of the junction of Carroll Canyon Road and Miramar Road, north of Miramar Road and 1 mile east of Interstate 805, east of Brown Field, 0.5 mile south southeast of the Alta School [historic site] on Otay Mesa, on the southeastern edge of Sweetwater Reservoir, near Artesian Road 1.25 miles east of the junction of El Mirador road and El Vuelto Road, a vague site 1 mile north of San Marcos near Twin Oaks Valley Road, a western finger canyon of the southwestern arm of Otay Mesa, above Dennery Canyon along Highway 117 on Otay Mesa, and just west of La Media Road 1.5 miles south of Brown Field. A recent report is from near Davis Road by the San Jacinto Wildlife Preserve, and east of California Street and north of the railroad tracks near Hemet in western Riverside County; old reports are from Skunk Hollow. A very large population numbering in at least the tens of thousands grows in a massive vernal pool on the corner of Stowe Road and California Road near Hemet. A substantial population grows in a vernal pool one half mile east of Los Caballos Road and south of Highway 79 near Vail Lake. Data Base reports for Riverside County are from 1 mile east of Perris, just northeast of the intersection of California Road and Marvin Hull Road near Perris, and in the San Jacinto Wildlife Area east of Davis Road and north of the San Jacinto River levee.
Twenty-four collections are found in the San Diego Herbarium; south to 30 28' North where collected by Moran (SD 100928) north of Ejido Papalote. This species is common in the vernal pool complex north of Cerro Bola and west of the Tecate/Ensenada Highway at Valle de las Palmas, Baja California.
Status: Spreading Navarretia is severely declining throughout its range. Much of it habitat on Otay Mesa is now being developed following rezoning of the area. N. fossalis is now extremely rare on the mesa, growing in only a few of the remaining southernmost pools. All sizeable populations should be protected; substantial portions of smaller populations are also recommended for protection.
Copyright © May 1994 Craig H. Reiser.