Western Dichondra [Dichondra occidentalis House]

Western Dichondra [Dichondra occidentalis House]

Listing CNPS List 4 R-E-D Code 1-2-1

State/Federal. Status -- /C3c CONVOLVULACEAE Mar.-May

Global Rank G3 State Rank S3.2

Distribution: Sonoma and Marin counties (questionable) disjunct to San Barbara County south and along the coast to Baja California.

Habitat: Southern Mixed Chaparral, Diegan Sage Scrub, rocky outcrops in grasslands, and especially recently exposed areas of post-burn habitat are all sometimes occupied by this small, cryptic perennial herb. It often grows almost completely hidden at the base of leafy shrubs. Soil tolerances for Dichondra appear variable with Loamy alluvial land of the Huerhuero complex utilized at Torrey Pines, Hambright gravelly clay loam in the San Onofre Mountains, and a variety of other types elsewhere.

Known Sites: Western Dichondra is occasionally common following burns in coastal San Diego County, as near Black Mountain Road south of Peñasquitos Canyon. It is potentially present at many county sites in coastal Chaparral or Diegan Sage Scrub. It is abundant on the slopes above the ocean at the Torrey Pines Preserve as a dominant understory element. Dichondra is a widely dispersed understory plant in Military Sector Alfa Two on Camp Pendleton with sightings extending throughout the San Onofre Mountains. It is expected to be abundant following a fire which burned most of the coastal slope of this range in 1990. Among other sites are the Jamul Mountains north of the glider port and Lower Otay Lake, on the peak east of Interstate 15 and south of Poway Road, on the southern slopes of Otay Mountain, the hills east of Massachusetts Avenue and north of Freeway 94, south of Del Mar Heights Road and east of El Camino Real, near Windmill Lake Golf Course on Camp Pendleton, near the northren terminus of Kearney Villa Road in the City of San Diego, and north of Poggi Canyon in Chula Vista. Three reports are from Fortuna Mountain, south of Poway Road on a slope at the end of Cobblestone Creek Road, and the top of Poway Grade; however, most historical sites are clustered near the immediate coast. Limited populations were seen at the head of Wruck Canyon near the Mexican border, east of Ruffin Road and just south of Highway 52, north of Swallowtail Lane in Encinitas, near Canyon Drive in Oceanside, close to the intersection of Questhaven and Elfin Forest Road, and near the Wire Mountain housing on Camp Pendleton. Some representative herbarium specimens include the summit of Mother Miguel Mountain, north of the Del Mar Racetrack, south of Gonzales Canyon and east of El Camino Real, the southeast side of Osuna Valley, San Marcos Creek, the bluffs north of Jefferson High School in Oceanside, and on Spooner's Mesa in the Tijuana Hills. Among the numerous reported sites are 0.25 mile north of the San Ysidro Border Station, on Soledad Mountain near the radio towers, near Inspiration Drive and Terryhill Drive in La Jolla, near La Jolla Rancho and Ravenswood Road and La Jolla Corona Drive, near Kearney Villa Road by the checkered water tank, near Mesa College west of Linda Vista Road, on a ridge on the southwest side of Fortuna Mountain, near the glider port and Salk Institute at Torrey Pines, east of Pine Needles Drive and Hidden Pines Road in Del Mar, east of Via Torina off Carmel Valley Road, in a tributary of Gonzales Canyon west of Black Mountain Road in North City West, north of Via de la Valle near Nardo Avenue in Del Mar, west of the El Camino Memorial Park along the side of Carroll Canyon Road, northwest of Camino Ruiz in North Mira Mesa, 1 mile east of Scripps Ranch, at the end of Santa Fe Drive between J and K Streets in Encinitas, scattered about Lux Canyon in Encinitas, in Solana Beach on the south side of San Elijo Lagoon, north of Agua Hedionda Creek and west of Dawson-Los Manos Reserve in Carlsbad, on the south side of Agua Hedionda Lagoon between the railroad tracks and Interstate 5, 1 mile south of San Francisco Peak, 1.5 miles northwest of Loma Alta Mountain, north of Ramblas de las Flores Road in Rancho Santa Fe, east of Whispering Palms Golf Course in Fairbanks Ranch, and north of San Marcos Gorge and 1 mile south of Rancho de los Quiotes. Old biological survey reports note sites in the Calavera Hills near Lake Calavera, near Pomerado Road between Carroll Canyon and San Clemente Canyon, between La Glorieta Road and Rambla de las Flores Road, south of Carlsbad and north of Agua Hedionda Creek, Sundance Avenue near Carmel Mountain Road, Dictionary Hill, in Carroll Canyon east of El Camino Memorial Park, south of San Dieguito Road and the Fairbanks Golf Course. This species is rare at Dana Point in Orange County on bluffs near the ocean. It is reported in La Jolla Valley and Deer Canyon in Ventura County; the ridge between Tuna and Topanga Canyon in Los Angeles County, as well as at Point Mugu and at Leo Carillo State Park.

Thirteen specimens from the herbarium at the San Diego Natural History Museum are recorded; south to 31 1' North where collected by Moran (SD 105343) three and a half kilometers east of El Rodeo. It can be seen on the eastern slope of Banda Peak at Punta Banda in Baja California and is locally common in sage scrub openings in Guadalupe Valley.

Status: Western Dichondra is slowly declining in coastal Southern California and is a borderline species for inclusion on the CNPS list. Sites with very high densities are noteworthy; in such circumstances substantial portions of these populations should be protected.

Copyright © May 1994 Craig H. Reiser.

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