Smooth Tarplant [Hemizonia pungens (Hook. & Arn.) Torrey & Gray ssp. laevis Keck]

Smooth Tarplant [Hemizonia pungens (Hook. & Arn.) Torrey & Gray ssp. laevis Keck]

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

State/Federal. Status -- /C2 ASTERACEAE Apr.-Sep.

Global Rank G5T2 State Rank S2.1

Distribution: San Diego County, Los Angeles County, Orange County, Riverside County, San Bernardino County, and Kern County

Habitat: Valley and foothill grasslands, particularly near alkaline locales, are the preferred habitat. Hanford coarse sandy loams are found at both the Hemet and the Sycamore Canyon Park locale. Smooth Tarplant generally grows at sites with minimal shrub cover. Plants south of Lake Hemet occur in a habitat which is quite alkaline and marshy in the spring following good winter rains. The flora here is quite unusual and distinctive and includes Atriplex coronata var. notatior and Atriplex coulteri.

Sites: Two historical reports are from the San Luis Rey and Santee areas. Habitat near Santee may still be extant on the periphery of the current city. It is still found along Temecula Creek within the city environs north of Rancho California Road in western Riverside County, north of Cajalco Road and west of Alexander Street, and in the Sycamore Canyon Park drainage west of Eucalyptus Street and the City of Moreno Valley. A vigorous population occurs 0.5 mile southwest of Lakeview Hot Springs near Lake Perris in Riverside County. It is also reported at other nearby locales along the San Jacinto River, 1160 meters east of the Lake Skinner Dam just north of Tucalota Creek, at Clinton Keith Road just east of the Deer Creek development in a low drainage, at Potrero Creek near Beaumont, east of Reinhardt Canyon and north of Domenighani Valley, both southeast of the San Jacinto Reservoir and immediately to the north, east of the duck ponds at the San Jacinto Wildlife Reserve, and in Moreno Valley 1 mile south of Highway 60 on the west side of Nason Street south of Dracaea Avenue. The type specimen is from the San Bernardino Valley; one recent report is from Lyttle Creek. Reported by Roberts for Orange County.

Seven collections of Hemizonia pungens are found in the herbarium at the San Diego Natural History Museum for Baja California; south to 31 51' North where collected by Moran (SD 63637) 3 miles northwest of Ojos Negros. Some/most/all of these specimens may be ssp. laevis; both small and large flowered, more robust plants are grouped together.

Status: Smooth Tarplant is close to extirpation in San Diego County, and apparently severely declining in western Riverside County where it is being heavily impacted by flood control measures and residential development along major drainages. It is a strong candidate for State Endangered status. Significant portions of all populations of Smooth Tarplant should be protected.


Copyright May 1994 Craig H. Reiser.

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