Willowy Monardella [Monardella linoides Gray ssp. viminea (Greene) Abrams]

Willowy Monardella [Monardella linoides Gray ssp. viminea (Greene) Abrams]

Listing CNPS List 1B R-E-D Code 2-3-2

State/Federal. Status -- CE/C2 LAMIACEAE Jun.-Aug.

Global Rank G5T3 State Rank S2.1

Distribution: San Diego County; Baja California, Mexico

Habitat: Riparian scrub, usually at sandy locales in seasonally dry washes, is the typical habitat of this small subshrub. Generally there is no canopy cover and river cobbles may lie nearby; scattered Western Sycamores grow elsewhere in most of these drainages. Soils are mapped as Stony lands in West Sycamore Canyon and Riverwash in San Clemente Canyon.

Known Sites: One colony in San Clemente Canyon has been partially displaced by a new freeway spur for Highway 52. A vigorous Otay Mountain population of M. linoides has wider leaves than typical ssp. viminea and is similar to specimens collected by R. Moran in Baja California. Old reports from urban drainages are often either extirpated sites or endangered by peripheral urban impacts including activities such as horse and hiking trails along the canyon bottoms. A recent report comes from the upper reaches of West Sycamore Canyon. Old biological survey reports note populations in Carroll Canyon and Murphy Canyon. Data Base reports are from 2 miles west of Mira Mesa in Lopez Canyon, 1 mile northwest of Mira Mesa in Lopez Canyon, 1 mile northeast of El Camino Memorial Park in a tributary of Carroll Canyon, within the Carroll Canyon drainage, in Kearney Mesa 0.25 mile north of Miramar on the east side of Frontage Road, Carroll Canyon drainage 0.33 mile east of Interstate 15, Sycamore Canyon from Benchmark 471 upstream approximately 1.7 miles and along Clark Canyon to 1 mile from its mouth, scattered in San Clemente Canyon on Miramar Naval Air Station lands, in Murphy Canyon on the east side of Interstate 15, Spring Canyon 4.5 miles east of Miramar near the eastern boundary of Miramar Naval Air Station, and 0.3 mile south of Gooden Ranch in a side canyon to the west of Sycamore Canyon.

No specimens for subspecies viminea are found in the San Diego Herbarium from Baja California. However, 18 specimens recorded as variety hypoleuca are found here south to 32 3' North where collected by Moran (SD 94888) east of the main summit of Sierra Blanca. Some of these Baja plants are poorly differentiated from ssp. viminea. Taxonomic work is needed to clarify the range of the various subspecies.

Status: Willowy Monardella is severely declining in total numbers in San Diego County. The sandy embankments in major canyon riparian systems along the coast, which are the primary microhabitat of Willowy Monardella, are rapidly being developed or degraded. Horse and hiking trails are cumulatively quite damaging in some areas. It is seriously endangered throughout most of its range. The CalTrans mitigation site in San Clemente Canyon for plants lost during the expansion of Highway 52 showed virtually all tagged specimens dead when the location was visited in the summer of 1987. Yards away, a few "native" M. linoides were in full flower and thriving. Nursery stock planted was apparently not drought tolerant. Reports of this species are concentrated in riparian creeks primarily within northern areas of the City of San Diego; surrounding habitat is quickly being engulfed by urban development. All populations should be protected.

Copyright May 1994 Craig H. Reiser.

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