Ione Manzanita
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Sacramento Fish & Wildlife Office
Species Account
IONE MANZANITA
(Arctostaphylos myrtifolia)
CLASSIFICATION: Federal Threatened Species (Federal Register 64:28403 pdf; May 26, 1999)
CRITICAL HABITAT: None designated
RECOVERY PLAN: Ione plants (under development)
DESCRIPTION:
Ione manzanita (Arctostaphylos myrtifolia) is an evergreen shrub of the heath family (Ericaceae). Attaining a height of generally less than 4 feet, plants appear low and spreading. The bark is red, smooth, and waxy. Olive green, narrowly elliptic leaves are 0.2 to 0.6 inch long.
White or pinkish urn-shaped flowers appear from January to February. The fruit is more or less cylindrical.
Ione manzanita can be distinguished from other species in the same genus by its smaller stature and the color of its leaves. Some manzanita species have basal burls but this one does not. See Hickman (1993) in General Information about California Plants, below, for a detailed description of the species.
DISTRIBUTION:
Ione manzanita may occur in about 100 individual stands, which cover a total of about 1,000 acres. It occurs primarily on outcrops of the Ione Formation within an area of about 35 square miles in Amador County. In addition, a few disjunct populations occur in Calaveras County.
Ione manzanita is the dominant and characteristic species of Ione chaparral, where it occurs in pure stands. The Ione chaparral plant community occurs only on very acidic, nutrient-poor, coarse soils, and is comprised of low-growing, heath-like shrubs and scattered herbs. Ione manzanita also occurs in transitional zones with surrounding taller chaparral types, but it does not persist if it is shaded. The populations range in elevation from 190 to 1,900 feet, with the largest populations occurring at elevations between 295 and 900 feet.
THREATS:
Mining, disease, clearing of vegetation for agriculture and fire protection, habitat fragmentation, residential and commercial development, changes in fire frequency, and ongoing erosion threaten various populations of this plant. The species depends almost entirely on fire to promote seed germination.
STATE & CALIFORNIA NATIVE PLANT SOCIETY STATUS:
The California Native Plant Society has placed Ione manzanita on List 1B (rare or endangered throughout its range). Although the species has not been officially listed by the State of California, the Department of Fish and Game considers it to be "very threatened."
REFERENCES FOR ADDITIONAL INFORMATION:
Gankin, R., and Major, J. 1964. Arctostaphylos myrtifolia, its biology and relationship to the problem of endemism. Ecology 45:792.
Swiecki, T.J., and Bernhardt, E.A. 2003. Diseases threaten the survival of Ione manzanita (Arctostaphylos myrtifolia). Vacaville, CA.
U.S. Fish & Wildlife Service. 1999. Endangered and Threatened Wildlife and Plants; Determination of Endangered Status for the Plant Eriogonum apricum (inclusive of vars. apricum and prostratum) (Ione Buckwheat) and Threatened Status for the Plant Arctostaphylos myrtifolia (Ione Manzanita). Portland, Oregon.
General Information about California Plants
Photo credit: Ione Manzanita ©2000 George W. Hartwell Calphoto ID: 0000 0000 0501 0176
Prepared by Endangered
Species Div., Sacramento Fish & Wildlife
Office, U.S. Fish & Wildlife
Service
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