Arctostaphylos osoensis
Oso manzanita, Oso manzanita, Oso manzanita
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Family: Ericaceae · Type: Shrub · Native
Conservation status: CNPS 1B.2
Arctostaphylos osoensis (Oso manzanita) is a native California shrub in the Ericaceae family, recognized by deeply lobed clasping leaf bases.
Oso manzanita is a rare (CNPS 1B.2) California native shrub found in the southern Central Coast, specifically in the western Los Osos Valley of San Luis Obispo County, growing on dacite volcanic outcrops in chaparral at elevations of 50 to 375 meters. Flowering from December to February, this plant produces white to pink flowers in pendulous racemes with distinctive leaf-like bracts. Growing erect to 1 to 4 meters tall with a gray, shredding bark and slender branches, it features densely overlapping leaves that are dark green, shiny, and deeply lobed at the base. Its leaves are ovate to round-ovate, 1.5 to 3 centimeters long, with an obtuse tip and entire margin, appearing smooth or sparsely hairy. The fruit is a depressed-spheric berry 5 to 8 millimeters wide, with stones that may be variably fused or free.
Identification and appearance
Key characters: 32 sympatric species; deeply lobed clasping leaf bases are diagnostic
Habitat and range
Habitat: Dacite (volcanic) outcrops, chaparral
Elevation: 50-375 m
California counties: San Luis Obispo
Bloom period
Arctostaphylos osoensis blooms Dec-Feb.
Conservation status
CNPS 1B.2
How to tell it apart
vs Arbutus: Arctostaphylos fruits are smooth and mealy; Arbutus fruits are bumpy and juicy.; vs Rhus: Arctostaphylos has simple evergreen leaves; Rhus has compound deciduous leaves.; vs Quercus: Arctostaphylos has urn-shaped flowers and berry-like fruits; Quercus has catkins and acorns.; vs Xylococcus: Arctostaphylos leaves are flat; Xylococcus leaves have margins rolled tightly under.; vs Heteromeles: Arctostaphylos has urn-shaped flowers; Heteromeles has flat white flower clusters.
Frequently asked questions
Is Arctostaphylos osoensis native to California?
Yes. Arctostaphylos osoensis is native to California (recorded as native).
When does Arctostaphylos osoensis bloom?
Arctostaphylos osoensis blooms Dec-Feb.
Where in California does Arctostaphylos osoensis grow?
Arctostaphylos osoensis occurs in San Luis Obispo, at elevations of 50-375 m.
What plant family does Arctostaphylos osoensis belong to?
Arctostaphylos osoensis is in the Ericaceae family, genus Arctostaphylos.
Is Arctostaphylos osoensis rare or endangered?
Arctostaphylos osoensis carries California Rare Plant Rank 1B.2, state rank S1.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CNPS Rare Plant Inventory · Index of California Plant Names · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.