Parry's Tetracoccus [Tetracoccus dioicus Parry]
Listing CNPS List 1B R-E-D Code 3-2-2
State/Federal. Status -- /C2 EUPHORBIACEAE Apr.-May
Global Rank G3 State Rank S2.2
Distribution: San Diego County, Riverside County; Baja California, Mexico
Habitat: A low-growing Chamise Chaparral, with moderately dense canopy cover, is the typical habitat of this robust shrub. Usually the situations are quite xeric with only limited annual growth. This species shows a preference for Las Posas soils.
Known Sites: Parry's Tetracoccus is rare in the southern portions of San Diego County such as on McGinty Peak. It is occasional on the slopes and hillsides west of Dehesa School, and on the dry, open slopes of Sequan Peak. A small population is found near Huntley Road south of Rainbow. Hundreds were seen growing in an extensive population north of Magee Road near the Riverside County line in open, chamise dominated chaparral. A substantial colony grows in taller chaparral south of Klondike Creek along Wildcat Canyon Road. Several scattered colonies occur in the San Marcos Hills west of Twin Oaks Valley Road. A limited population occurs west of the aqueduct and north of Gregory Canyon and Highway 76 west of Pala. Old reports are from the Agua Tibia Mountains, Monserate Mountain, De Luz, and Tecate Junction. Old biological survey reports note sites east of Spangler Peak in San Vicente Valley, near Vista Romero Road in San Vicente Valley, west of Trujillo Creek and southwest of the Magee Truck Trail near the peak, on The Mesa southeast of the Singing Hills Country Club and west of Sloane Canyon, northeast of Red Mountain and Rainbow Creek, near Rainbow Glen Road on the west side of Rainbow Creek and Highway 163, near Rainbow Crest Road in Rainbow, northwest of Gold Circle Drive in the Merriam Mountains, and on Mount Olympus. Data Base reports for San Diego County are from Sequan Peak, Skyline Road about Lyons Valley, Jacumba, Barona Valley, near Pala between the Harguemayo and McGee Ranches, Red Mountain Grade on Highway 395 near Fallbrook, north of Rainbow Creek at the end of Hill Haven Drive, 1 mile south of Mount Olympus, 0.9 mile south southwest of Mount Olympus, and near Lone Palm Spring on the road to De Luz. Reported by the Data Base for Orange County east of the Lower San Juan Picnic Area in San Juan Canyon in the Santa Ana Mountains.
Six voucher specimens are found at the herbarium of the San Diego Natural History Museum for Baja California; south to 31 23' North where collected by Moran (SD 91545), 2 miles southeast of Santa Cruz.
Status: Parry's Tetracoccus is slowly declining. It is particularly susceptible to orchard expansion in the Pala Mesa region where clearance of chaparral for avocados and citrus has not historically required biological surveys to determine potential impacts to sensitive shrubs. It is being severely impacted by residential expansion into the San Marcos Hills. All substantial populations should be protected; substantial portions of smaller populations should be placed into protected, biological open space.
Copyright © May 1994 Craig H. Reiser.
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