

San Diego Barrelcactus Ferocactus viridescens
San Diego Barrelcactus is a perennial shrub native to the lower 48 states. It blooms Apr – Jun. A host for pollen-specialist native bees.
More about this plant
Ferocactus viridescens is a species of flowering plant in the cactus family Cactaceae. This barrel cactus is known by several common names, including coast barrel cactus, keg cactus and San Diego barrel cactus. Most of its native range in the United States is in San Diego County, California, where it is threatened by development, agriculture, and other alterations in its habitat. It is also found in northern Baja California, Mexico. Wikipedia →
Growing & care
USDA PLANTS · TRY- Hardiness
- ≥ zone 11 derived from its U.S. range
- Lifespan
- Perennial
- Foliage
- Evergreen
Wildlife & pollinators
How pollinator value is scored →❧ Caterpillar hosts Documented caterpillar host
Recorded feeding on Ferocactus in North America, including:
✦ Bees specialist-bee host · 4 bee visitors
Specialist native bees depend on it.
Some native bees are pollen specialists (oligolectic) — they raise young only on pollen from particular plant genera. Ferocactus is a recorded specialist-bee host, so losing it can mean losing the bee that relies on it.
4 native & managed bee species are documented visiting San Diego Barrelcactus :
How we know this (2) Methods & honest limits
A recorded categorical fact: each species is tagged C3 (standard), C4 (heat/water-efficient) or CAM (succulent, night-time CO₂ uptake) — or a facultative combination. We only show a trait card for the noteworthy C4/CAM cases; C3 is the unremarkable majority, kept in the data but not surfaced as a card.
We take the plant’s U.S. county range and look up each county’s long-term climate, then summarise: native rainfall = the median annual rainfall across its counties; heat tolerance = the warm end (90th percentile) of average temperature across its range (mirroring how our cold-hardiness floor uses an extreme). Counties + medians blunt the roadside/observer bias that makes point-level climate unreliable. Needs at least five placeable counties.
Honest limits: A realized, sampling-biased niche (where it has been recorded, not its physiological optimum), and county climate is coarse — large Western counties span deserts and mountains. Derived guide, never a measured fact.
Sources for this entry (21) Open & cited
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PlantKey’s data is open under CC BY-SA 4.0 — free to reuse and adapt, with attribution and the same licence. Photos keep their own per-image licence + credit (see Sources above).
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