Pedate Checker-mallow

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Pedate Checker-mallow

Sidalcea pedata

ListedAugust 31, 1984
FamilyMalvaceae (Mallow)
DescriptionMultistemmed perennial with lobedleaves and pinkish-rose flowers.
HabitatWet alkaline meadows.
ThreatsDams, loss of wetlands, residential development.


Pedate checker-mallow, Sidalcea pedata, is a multistemmed, perennial herb that grows from a fleshy taproot to a maximum height of about 10 in (25 cm). The erect stems range from being slightly hairy to bristly, and are typically reddish, especially in young plants. Leaves have three to five lobes, each subdivided into linear segments. Most leaves are grouped around the base of the plant. Many deep pinkish-rose flowers are gathered into a spike (raceme) along the ends of stems. The checker-mallow flowers from May to August and fruits from June to August.


The habitat for pedate checker-mallow is restricted to vernally moist meadows and sparsely vegetated drier meadows at elevations from 5,250-8,200 ft (1,600-2,500 m) in Big Bear Valley. Pedate checker-mallow is one of the indicator species used to define and delimit wet meadow habitats. Although the areas occupied by pedate checker-mallow and other rare species have traditionally been referred to as wet meadows, they might be more accurately described as moist meadows. Within wet meadow habitats, pedate checker-mallow tends to occupy relatively drier portions of the landscape. Individual plants generally are not found in the dense rush and sedge thickets typically found in the wettest portions of drainages, swales, and meadow areas.

It is essential that appropriate hydrological conditions be maintained within the moist meadow habitat. At Bluff Lake, pedate checker-mallow is found in the moist to drier parts of the meadow and is associated with other rare species. At a number of other sites, including the locale at the north end of Baldwin Lake, the species occurs in moist swales. In drier, more elevated portions of these meadows, pedate checker-mallow is interspersed with Artemisia tridentata and A. nova.

The moist to wet, open meadow association, where pedate checker-mallow is found, is often interspersed within pebble plains, another sensitive plant community in the Big Bear Valley area. In these wet meadow habitats, this species often occurs in association with other species considered to be rare.

Geologically, the basins that form Baldwin Lake and Big Bear Valley are both the result of deposition of lake-bottom and alluvial debris. The geological history of the area as a Pleistocene lake bed has resulted in a high clay component in the soil, which has contributed to the formation of wet meadow habitat. This wet meadow habitat occurs where clay layers in the soil are intercepted by shallow drainages or springs. The clay forms a barrier to percolatin of surface water and creates appropriate conditions for moist to wet meadow species. Clays occur in layers in soils that are characteristically gravelly to sandy. An associated study of groundwater availability suggests that groundwater may not provide significant moisture to the vegetation, which may rely instead on surface moisture from precipitation and snowmelt.


At one time, the pedate checker-mallow probably ranged throughout the Big Bear Lake Basin in San Bernardino County, California. Five of the historic occurrences were extirpated from flooding following the construction of Big Bear Dam.

As of 1998, pedate checker-mallow survived in significant numbers at 17 sites containing 23 populations near Bluff Lake, Baldwin Lake, and along the south shore of Big Bear Lake. The total area of these sites is estimated at about 14.5 acres (5.9 hectares). The only estimate of population was made in 1989 during a drought year, so that the estimate of 68,300 individuals may be low since moisture is probably a limiting factor. Much of the surrounding region falls within the boundaries of the San Bernardino National Forest, but all population sites are privately owned. Plants are occasionally found in vacant lots or waste areas in the midst of residential or commercial developments, but these scattered plants apparently do not reproduce well and are expected to die out.


Dam construction, drainage of wetlands, and diversion of water for irrigation or human use have reduced the original meadowland habitat of this species from 7,000 acres (2,850 hectares) to about 1,000 acres (400 hectares). Most historic colonies have been eliminated. During the 1980s and 1990s, residential subdivisions spilled into the mountains from the city of San Bernardino and threatened to claim much of the remaining habitat. Urbanization around Big Bear Lake and Baldwin Lake reduced much of the remaining habitat, leaving highly restricted and isolated pockets of surviving pedate checker-mallow.

Habitat conditions, particularly the abundance and quality of groundwater, have deteriorated since the checker-mallow was surveyed in 1978 and 1980. Off-road vehicle use and development have altered the natural surface runoff and drainage patterns, resulting in further degradation of habitat. In the areas around South Baldwin Lake, Pan Hot Springs, and Metcalf Bay, intensive livestock grazing has destroyed some of the habitat. Livestock trample the tuberous root crowns when the ground is saturated, and it compacts the soil. The result is extirpation of the pedate checker-mallow on grazing lands. Pedate checker-mallow has also been crowded out of some habitats by introduced plant species, particularly Agropyron ssp.

Conservation and Recovery

The recovery plan for pedate checker-mallow recognizes that protection of the remaining habitat is essential to preserving the species. The U. S. Fish and Wildlife Service recommends acquiring lands and easements through agreements with owners that would permit land managers to restrict certain agricultural practices, grazing, development, and off-road vehicle use. An alternative to purchasing land is land use zoning. Former habitats could be restored if grazing and vehicular use ceased, and if the water table can be maintained at a suitable level. This species requires the presence of a vernal supply of water, and alteration of natural surface hydrology will cause its decline. The pedate checker-mallow will recover rather quickly after grazing has ceased if mature plants are still present in the affected habitat.

Limited information exists on the success of transplantation of pedate checker-mallow plants based on experimental projects in the Big Bear Valley. In the early 1980s, 12 pedate checker-mallow plants were transplanted from the site of an impending development to the Belleville site in Upper Holcomb Valley on U. S. Forest Service (USFS) land. This experimental population is presumed to be extirpated.

A second experimental transplant project occurred as partial mitigation for a development in Big Bear City. In 1988 and 1990, 13 mature and four seedling pedate checker-mallow plants were transplanted from a private property parcel to the Nature Conservancy's property on Garstin Drive. Six of the mature transplanted plants were observed during a 1991 survey of the transplant site. Apparently, however, none of the seedlings survived. In a subsequent survey during 1993, only three of the original transplanted adult plants were found, and the transplanted population did not appear to be self-perpetuating. Competition with introduced weeds may have reduced the success of the transplanted individuals. Thus far, transplantation has not been confirmed as a successful method of restoring, mitigating, or enhncing pedate checker-mallow populations. Further research into the efficacy of transplantation methodologies is necessary.

The USFS retains ownership of one locale of pedate checker-mallow at Ski Beach. This site is entirely fenced to protect the species. Annual monitoring of the species has been conducted by Big Bear Ranger District staff since 1989. A total population census was conducted in 1989 and monitoring of permanent plots was undertaken in 1990, 1991, and 1992. The USFS, specifically the Big Bear Ranger District botanist, has participated in a cooperative monitoring program with the Nature Conservancy and the California Department of Fish and Game that was initiated in 1989.


U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121


Kantz, T. P. 1979. "A Botanical Investigation of Sidalcea pedata. " U. S. Forest Service, San Bernardino.

U. S. Fish and Wildlife Service. 1998. "Recovery Plan for the Pedate Checker-mallow and Slender-Petaled Mustard." U. S. Fish and Wildlife Service, Portland. 68 pp.