Island Malacothrix

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Island Malacothrix

Malacothrix squalida

ListedJuly 31, 1997
FamilyCompositae (Asteraceae)
DescriptionAn annual, herbaceous wildflower with light yellow flowers.
HabitatCoastal bluffs.
ThreatsHabitat degradation and direct consumption by introduced mammals, and competition with alien plants.


Malacothrix squalida (island malacothrix) was described in 1886 from specimens collected from an islet off the northern shore of Santa Cruz Island. In 1957, the combination Malacothrix foliosa var. squalida was published and a year later was published as Malacothrix insularis var. squalida. In 1959, the taxon was recognized as Malacothrix squalida, but 14 years later it was synonymized with Malacothrix foliosa. In a review of insular species of Malacothrix, the taxon was recognized as Malacothrix squalida, a treatment which was recently retained.

Malacothrix squalida is an annual herb in the aster family. Unlike Malacothrix indecora, the plant reaches only 3.5 in (9 cm) tall, and has linear to widely lanceolate leaves that are irregularly toothed or lobed. The light yellow flowers are clustered in hemispheric heads 0.5-0.6 in. (12-15 mm) long. Malacothrix indecora is the only other annual Malacothrix that occurs on the same island as Malacothrix squalida ; however, the latter is a much larger species, and also differs in the achene characteristics previously mentioned.


Malacothrix squalida occurs in coastal bluffs.


Malacothrix squalida has been collected from two locations along the north shore of Santa Cruz Island.

It was collected near Prisoner's Harbor in 1886, but the species was not seen on the island again until it was collected in 1968 near Potato Harbor, where sheep overgrazing is a major problem. On Middle Anacapa Island, the plant was first collected by Martin Piehl in 1963, and again in 1978 and 1986. The plant was known from several small colonies atop coastal bluffs on the east end of the island. Surveys in 1989 failed to find any individuals; however, this may have been due to the drought that year. Although Malacothrix squalida has not been seen in recent years, all historical localities and potential habitat for the species have not been inventoried.


All of the historical localities for Malacothrix squalida are impacted by soil loss, habitat alteration, sheep grazing, and feral-pig rooting. Any extant populations are also likely to be threatened by these factors. Seabird nesting may have localized impacts to some populations on Middle Anacapa Island.

Conservation and Recovery

The island malacothrix may survive as several tiny populations on Santa Cruz and Middle Anacapa Islands. The broader habitat on these islands is being conserved in a relatively natural condition in the Channel Islands National Park, and by the Nature Conservancy, a private conservation organization. However, the island malacothrix and other rare plants are severely threatened by the feeding of sheep, pigs, and other introduced mammals. The protection of the endangered malacothrix requires that these herbivores be reduced or eliminated from its habitat. The abundance of invasive alien plants should also be reduced or eliminated, because they are providing intense competition to native species. The populations of the island malacothrix should be monitored, and research undertaken into its biology and habitat needs, including methods of management that would benefit the endangered plant. A captive-propagation program should be developed, to provide stock for out-planting to supplement the tiny natural population, and to reestablish additional populations in suitable habitat.


U. S. Fish and Wildlife Service
Ventura Fish and Wildlife Office
2493 Portola Road, Suite B
Ventura, California 93003
Telephone: (805) 644-1766
Fax: (805) 644-3958

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


U.S. Fish and Wildlife Service. 1997. "Endangered and Threatened Wildlife and Plants; Final Rule for 13 Plant Taxa from the Northern Channel Islands, California." Federal Register 62 (147): 40954-40974.