Cylindropuntia fosbergii
Fosberg's or mason valley cholla, Fosberg's Or Mason Valley Cholla
Photo by Chez Brungraber
Family: Cactaceae · Type: Shrub · Native
Conservation status: CNPS 1B.3
Cylindropuntia fosbergii (Fosberg's or mason valley cholla) is a native California shrub in the Cactaceae family, recognized by thick easily-detached segments and pale red-brown flowers.
Fosberg's cholla is a rare California native shrub ranked 1B.3 by CNPS, found in eastern San Diego County on valley floors and alluvial fans at elevations of 300 to 450 meters. Flowering from March to May, this plant produces pale red-brown flowers with green filaments. Growing up to 2.5 meters tall with several long, curving branches, it forms distinctive terminal segments that are easily detached. Its branches feature 7 to 10 pale red-brown spines less than 2.5 centimeters long, covering pale yellow-brown spine sheaths. The plant has long, curved branches with terminal segments about 4 to 6 centimeters in diameter, giving it a distinctive, sculptural appearance in its desert habitat.
Identification and appearance
Key characters: 9 sympatric species; thick easily-detached segments and pale red-brown flowers
Habitat and range
Habitat: Valley floors, alluvial fans
Elevation: 300-450 m
California counties: San Diego
Bloom period
Cylindropuntia fosbergii blooms Mar-May.
Conservation status
CNPS 1B.3
How to tell it apart
vs Opuntia: Cylindropuntia has cylindrical stem segments; Opuntia has flattened paddle-shaped pads.; vs Austrocylindropuntia: Cylindropuntia has papery spine sheaths that peel away; Austrocylindropuntia lacks spine sheaths entirely.; vs Echinocereus: Cylindropuntia has segmented stems that detach easily; Echinocereus has ribbed continuous stems.; vs Bergerocactus: Cylindropuntia has detachable segments with tubercles; Bergerocactus has continuous ribbed stems.; vs Grusonia: Cylindropuntia has round spines and grows waist-high or taller; Grusonia has flattened spines and stays under 10 inches.
Frequently asked questions
Is Cylindropuntia fosbergii native to California?
Yes. Cylindropuntia fosbergii is native to California (recorded as native).
When does Cylindropuntia fosbergii bloom?
Cylindropuntia fosbergii blooms Mar-May.
Where in California does Cylindropuntia fosbergii grow?
Cylindropuntia fosbergii occurs in San Diego, at elevations of 300-450 m.
What plant family does Cylindropuntia fosbergii belong to?
Cylindropuntia fosbergii is in the Cactaceae family, genus Cylindropuntia.
Is Cylindropuntia fosbergii rare or endangered?
Cylindropuntia fosbergii carries California Rare Plant Rank 1B.3, state rank S2.
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.