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Ione Manzanita
(Arctostaphylos myrtifolia )

Ione manzanita
BLM Photograph

Description: Ione manzanita is a small, evergreen shrub, usually less than four feet (1.2 meters) tall and commonly only two feet (0.6 meters) tall.  Its bark is red, smooth and waxy. Leaves are small, 1/4 to 1/2 inch (6 to 15 mm), oval in shape, pointed at the tip, and often pointed at the base as well. They are light green and shiny. The white to pinkish urn-shaped flowers are also small, averaging 1/8 inch (4 mm) across. Its small, rounded, greenish fruits are 1/8 inch (3 to 4 mm) long and 1/16 inch (2 to 2.5 mm) wide. This manzanita species lacks a basal burl. (A basal burl is a swelling at the junction of roots and stems that allows many chaparral shrub species that are equipped with this organ to sprout from the base and vegetatively regenerate after a fire that kills the shrub canopy.) After a fire, Ione manzanita must regenerate from seed.

Distribution: The center of distribution of Ione manzanita is the large exposure of the Ione formation in western Amador County and adjacent Calaveras County. Elevations here range from 200 to 460 feet (60 to 140 meters). In addition there are a few occurrences north of San Andreas in Calaveras County, ranging up to 1800 feet (550 meters) in elevation. BLM manages Ione manzanita habitat at the Ione Manzanita ACEC north of the east end of Lake Comanche, and on 60 acres (24 hectares) of public land approximately 6 miles (10 kilometers) northwest of Ione.

Habitat: Ione manzanita is mostly confined to the unusual soils of the Ione formation. These soils are highly acidic and contain high levels of aluminum.  (Aluminum in high concentrations can be toxic to plants.) Organic matter and nutrient availability is low. Although there are areas within the Ione formation where soils have become more fertile with recent soil development, Ione manzanita occupies sites where the extreme conditions described above persist. This soil environment is extremely hostile to the growth of most plants. Ione manzanita commonly grows in pure stands. At the edge of these stands there may be a transition zone where Ione manzanita and whiteleaf manzanita coexist. Other dominant plants of the region include chamise, interior live oak and foothill pine.

Flowering Period: January to February

Similar Plants: The other dwarf manzanita of the central Sierra foothills, Nissenan manzanita, Arctostaphylos nissenana, is known only from Eldorado and Tuolumne Counties and typically grows at higher elevations. Nissenan manzanita has rough fibrous bark. The leaves of Nissenan manzanita are longer, 1/2 to 1 inch (1 to 2.5 cm), than those of Ione manzanita, 1/4 to 1/2 inch (0.6 to 1.5 cm). Nissenan manzanita leaves are pale green and dull. The bracts on the lower portion of the inflorescence of Nissenan manzanita are leaf like in shape. All the inflorescence bracts of Ione manzanita are small, scale-like and triangular.

Status: Federal Threatened, California Native Plant Society List 1B

Field Office: Mother Lode

Last updated: 08-05-2010