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

State/Federal. Status -- /C2 FABACEAE Apr.-Jun.

Global Rank G5T2 State Rank S2.2

Distribution: San Diego County, Imperial County; Baja California, Mexico

Habitat: Open chaparral, often a transmontane desert phase, is the preferred U.S. habitat of this herbaceous perennial. Mild soil disturbance may encourage growth of this species which occurs with Adenostoma fasciculatum in relatively exposed, xeric locales. Geraea viscida is another sensitive species which may grow sympatrically with the Jacumba Milk Vetch. La Posta loams are the soil type found with the Live Oak Springs populations near Miller Valley.

Known Sites: Jacumba Milk Vetch can be found along Highway 94 east of Cameron Corners. Scattered individual plants were seen south of Miller Creek and west of Miller Valley on mildly disturbed road shoulders where there was little competition from other species. Variety perstrictus has an erect habit and distinct aspect quite dissimilar to common A. douglasii var. parishii of the mountains of southeastern San Diego County. Jacumba Milk Vetch's habitat is primarily transmontane, high desert chaparral. This plant is little known owing to its occurrence in a very lightly populated area of San Diego County; nevertheless, a number of scattered reports from Buckman Springs to Bankhead Springs indicate Jacumba Milk Vetch occurs at a substantial number of locales. Old reports include Lark Canyon, Eckener Pass, Campo, Tierra del Sol, and Jacumba. Old biological survey reports note sites just south of Boulevard, near Starship Road and the community of Manzanita south of Highway 94, 2 miles south of Tierra Del Sol on Tierra Del Sol Road, 1.2 miles south of Bankhead Springs, south of the Calexico Lodge and southeast of Manzanita, along McCain Valley Road, between Interstate 8 and Highway 94 south of Boulevard, and 0.5 mile north of Manzanita and east of Jewell Road. This species likely extends into Imperial County south of In-Koh-Pah Park. Data Base reports are for scattered locales in the vicinity of the McCain Valley including near the Cottonwood Campground, south of the McCain Valley Road's terminus, on Canebrake Road, south of the intersection of McCain Valley Road and Lost Valley Road, in Lark Canyon Campground, near Mount Tule, in Pepperwood Canyon, near the Manzanita/Cottonwood Road, near a road intersection to Table Mountain, 0.25 mile south of McCain Valley Road and north of Lost Valley Road, and south of Table Mountain paralleling Interstate 8. Another Data Base entry is for the Manzanita Indian Reservation adjacent to the reservoir along Tule Creek. Plants growing near Temecula Creek south of Aguanga in Riverside County show strong tendencies towards variety perstrictus and grow in a similar semi-desert microhabitat and could represent a northern disjunct population of Jacumba Milk-vetch.

This plant grows south in Baja California to 31 44' North where collected 2 miles west of Cerro Colorado by Moran (SD 83919). Only 7 collections from Baja are deposited at the San Diego Natural History Museum's herbarium; pinyon and juniper woodland is its preferred habitat south of the border.

Status: Populations of Jacumba Milk Vetch are presently stable in the United States, owing to limited development of its transmontane, desert habitat. Substantial portions of large populations are recommended for protection.

Copyright May 1994 Craig H. Reiser.

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