Sclerocactus brevispinus

Sclerocactus cloveriae ssp brackii

Sclerocactus glaucus

Sclerocactus parviflorus

Sclerocactus parviflorus 'intermedius'

Sclerocactus parviflorus `contortus'

Sclerocactus polyancistrus. Nevada

Sclerocactus pubispinus (Utah)

Sclerocactus spinosior

Sclerocactus whipplei

Sclerocactus wrightiae

Solisia pectinata

Stenocereus alamosensis (Octopus cactus). Syn. Rathbunia alamosensis. USDA: 9b-10. Full sun. Little water. Hardy to 28°F. Thicket of bending stems, up to 10 ft tall. Tubular pinkish red flowers, attracts hummingbirds. Origin: Mexico (Chihuahua and Sonora)

Stenocereus chrysocarpus

Stenocereus dumortieri.  USDA: 10. Hardy to 23°F. Full sun. Heat tolerant. Little to moderate water. Fast growing, tree like cactus. Can reach 50' tall. White flowers. Origin: South-central Mexico.

Stenocereus pruinosus (Stenocereus griseus). Mexican organ pipe. USDA: 10. Full sun. Heat tolerant. Little to moderate water. Hardy to 23°F. Fast growing to 20' tall. Origin: South-central Mexico.

Stenocereus queretaroensis. USDA: 9b-11. Light shade to full sun. Hardy to 28°F. Tree-like growth, with stems to 18'. Pale pink flowers. Origin: Mexico.

Stenocereus thurberi (Arizona organ pipe). Sunset: 12-24; USDA: 9b-12. Full sun. Heat tolerant. Little to moderate water. Hardy to 24° F. Fast growing, with regular water to 20' tall. Origin: Southern Arizona, northern Mexico.

Stenocereus weberi.  USDA: 10. Hardy to 28° F. Full sun. Heat tolerant. Little to moderate water. Fast growing, tree like cactus, an reach 30' tall, 30' spread. Yellowish white flowers. Origin: South-central Mexico.

Stetsonia coryne (Argentine toothpick) Sunset: 12-13; USDA: 9-11. Full sun. Heat tolerant. Little to moderate water, summer. Hardy to 18°F. Branching cactus to 20 feet tall. Origin: Low deserts of Argentina, Bolivia.

Strombocactus disciformis

Strombocactus disciformis v. jarmilae

Strombocactus disciformis v. seidelii

Strombocactus pulcherrimus

Submatucana madisoniorum v. asterium

Submatucana senilis