Plants are found growing on granite slopes and xeric scrub in Baja California, Mexico at elevations around 110 to 2600 meters. Plants are found growing along with
Adenostoma fasciculatum,
Stipa speciosa,
Arctostaphylos peninsularis,
Dudleya pulverulenta,
Lotus rigidus,
Nolina microcarpa,
Pinus monophylla,
Rhamnus crocea,
Opuntia phaeacantha,
Cylindropuntia acanthocarpa,
Pinus quadrifolia,
Ferocactus viridescens and
Malosma laurina. File:Echinocereus pacificus pacificus 3.jpg|
Echinocereus pacificus subsp. pacificus in Ensenada, Baja California, Mexico File:Echinocereus pacificus mombergerianus.jpg|
Echinocereus pacificus subsp. mombergerianus growing in San Pedro Mártir, Baja California, Mexico ==Taxonomy==