Coastal San Diego County  and Baja California, Mexico .
Twenty-five occurrences on Conserved Lands in MUs 1 (Tijuana River Valley Regional Park), 2 (El Dorado Hills, Florida Canyon, Kate Sessions Park, Mission Trails Regional Park), 3 (East Otay Mesa, Marron Valley Mitigation Bank, Otay Mountain Ecological Reserve, Otay Mountain Wilderness Area, Otay Ranch Preserve, Rancho Jamul Ecological Reserve, San Diego National Wildlife Refuge, Sweetwater Reservoir Open Space), 4 (Mission Trails Regional Park, South Poway Cornerstone, Sycamore Canyon), 6 (Black Mountain Open Space Park, Los Penasquitos Canyon Preserve, Lusardi Creek Preserve, Santa Fe Valley Open Space Preserve, Torrey Pines State Natural Reserve), and 7 (Torrey Pines Glider Port).
Chaparral, coastal scrub, valley and foothill grasslands, and vernal pools . Sandy or gravelly soils of hillsides of chaparral . Elevation range 3-450 meters . Sensitive to freezing .
Cactaceae family . Synonym: Echinocactus viridescens.
Perennial stem succulent . Ant-plant protection mutualism .
Bloom period May-June .
Pollinated mainly by bees: cactus bees (Diadasia spp.), honey bees (Apis mellifera), and small native bees .
Urbanization has fragmented and extirpated the species from some locations . Additional threats from vehicles, horticultural collecting, agriculture, non-native plants, and Argentine ants [2, 4].
Floral visitation by invasive Argentine ant (Linepithema humile) reduces pollinator visitation and seed set .