Kern Mallow

Eremalche kernensis

Description

The height and habit of Kern mallow (Eremalche kernensis ) vary depending on seasonal precipitation. The form can vary from single-stemmed to multiple-stemmed, with the central stem erect and the lateral stems trailing along the ground. Stem lengths at flowering may range from less than 1 in (less than 2.5 cm) to 20 in (50.8 cm). The flowers have five petals, and the wheel-shaped fruits are divided into single-seeded segments.

The most recently published treatments assign Kern mallow the name E. parryi ssp. kernensis. However, the taxonomy of Kern mallow remains controversial in terms of its rank and its relationship to Parry's mallow, E. parryi ssp. parryi.

The taxonomic debate centers around the gender, color, and size of flowers indicative of Kern mallow versus Parry's mallow. Some populations in the Kern/Parry's mallow complex exhibit a condition known as gynodioecy, meaning that a population contains a mixture of plants that have only female flowers and plants that have only bisexual flowers (with both male and female parts).

Bisexual Kern mallow flowers produce fewer seeds per fruit (seven to 13) than do pistillate (female) flowers (eight to 19). Parry's mallow and desert mallow fruits contain 10-22 and nine to 13 segments, respectively.

The strictest definition of Kern mallow applies only to populations in which white flowered individuals predominate. Even in these areas, a few individuals may have pale lavender flowers, but lavender flowered plants represented less than 10% of one population in 1994. Definite Parry's mallow populations consist of only pinkish-purple flowers, whereas those of questionable taxonomic affinity contain either exclusively pinkish-purple flowers or a very small proportion of white flowered plants. Regardless of color, pistillate flowers have shorter petals than bisexual flowers in the same population. Parry's mallow has larger flower parts than Kern mallow. Another closely related species that infrequently occurs with the other two taxa is desert mallow, which has trailing stems and bisexual flowers that are smaller than those of Kern mallow.

As with many arid-land annuals, the form, density, phenology (timing of different stages in the life cycle), and reproduction of Kern mallow vary greatly depending on precipitation.

In Lokern (the local name for the area between Buttonwillow and McKittrick in southern California), Kern mallow seeds typically germinate in January and February, and the plants begin flowering in March. Fruit production begins within a few days after flowers appear; flower and fruit production may continue into May if sufficient moisture is available. The seeds fall from the fruits as soon as they are mature. Seeds are capable of germinating in the following growing season, but at least some remain ungerminated. The duration of seed viability in the soil is not known. Seed dispersal agents are unknown but probably include animals and wind.

Habitat

Kern mallow typically occurs in the Valley Salt-bush Scrub natural community, where it grows under and around spiny and common saltbushes and in patches with other herbaceous plants, rather than in the intervening alkali scalds. Associated herbs include red brome, red-stemmed filaree, woolly goldfields, and white Sierran layia. Kern mallow typically grows in areas where shrub cover is less than 25%. The amount of herbaceous cover varies with rainfall and microhabitat; in occupied areas of Lokern, herbaceous cover averaged 80% in 1993 and 48% in 1994. Kern mallow occasionally has rein-vaded disturbed sites when existing populations remained in adjacent areas to provide sources of seed.

Kern mallow occurs on alkaline sandy loam or clay soils at elevations of 315-900 ft (96-274.3 m). Kern mallow grows on soils that are more alkaline, less saline, and less sandy than those where Parry's mallow grew.

Distribution

Kern mallow has always had a highly restricted distribution in western Kern County, California, north of McKittrick. A 1986 status survey reported three additional occurrences in Lokern. More intensive surveys conducted in the early 1990s revealed that Kern mallow occurs intermittently within an area of approximately 40 sq mi (103.6 sq km) in Lokern. The California Native Plant Society and California Department of Fish and Game received reports in 1994-95 of Kern mallow from three sites between Maricopa and McKittrick.

Threats

The loss and degradation of habitat in the Lokern area have been responsible for the decline of Kern mallow. Construction of the California aqueduct impacted Kern mallow both directly, by destroying plants in its path, and indirectly, by providing water that allowed cultivation of cotton and alfalfa in the area of endemism. The western portion of Lokern was developed for petroleum production, which eliminated Kern mallow. Two disposal facilities for liquid waste were constructed in occupied habitat. Causes of habitat degradation— not only in Lokern but also in the populations south to Maricopa—included installation of pipelines and transmission lines and off-road vehicle use. The pesticide Malathion is sprayed on surrounding natural lands to control the beet leafhopper, and may also kill some of the pollinators of Kern mallow.

Efforts to conserve Kern mallow include research on its reproductive biology, salvage of plant specimens and seed from the Laidlaw Waste Disposal Facility, ongoing population monitoring and research on the response of Kern mallow to cattle grazing, and exclusion of grazing from Kern mallow habitat.

Conservation and Recovery

Oil and gas exploration destroyed the first known population of Kern mallow; conversion of land to agricultural production is responsible for the loss of the population north of Lost Hills. Remaining populations are near active oil and gas fields and are vulnerable to further development. All surviving populations are in areas grazed by sheep during the winter and spring. If this grazing becomes heavy and is not controlled, it could adversely affect the remaining Kern mallow populations.

Contacts

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

Sacramento Field Office
Federal Building
2800 Cottage Way
Sacramento, California 95825-1846
Telephone: (916) 414-6446
Fax: (916) 414-6486

References

Brown, D. E. 1982. "Californian Valley Grassland."Desert Plants 4: 132-135.

Heady, H. F. 1977. "Valley Grassland." In Terrestrial Vegetation of California, edited by M.G. Barbour, and J. Major. John Wiley and Sons, New York.

Hoover, R. F. 1970. The Vascular Plants of San Luis Obispo County, California. University of California Press, Berkeley.

McNaughton, S. J. 1968. "Structure and Function in California Grasslands." Ecology 49: 962-972.

Ornduff, R. 1974. An Introduction to California Plant Life. University of California Press, Berkeley.

Taylor, D. W., and W. B. Davilla. 1986. "Status Survey of Three Plants Endemic to the San Joaquin Valley." U. S. Fish and Wildlife Service, Sacramento.

Wester, L. 1981. "Composition of Native Grasslands in the San Joaquin Valley, California." Madrono 28: 231-241.