Syn.: Cereus pectinatus var. rigidissimus Engelm., Echinocereus dasyacanthus var. rigidissimus (Engelm.) W. T. Marshall, Echinocereus pectinatus var. rigidissimus (Engelm.) Rumpler
Family: Cactaceae Juss.
Echinocereus rigidissimus
Distribution: Endemic to Sonora desert, found in relatively small area on the border of US and Mexico. Grows on both sides of border between New Mexico and Arizona and between states of Chihuahua and Sonora in Mexico. Besides the nominate subspecies another subspecies is recognized – red-spined subsp. rubrispinus.
Echinocereus rigidissimus

Echinocereus rigidissimus

Ecology: Found in desert, semi-desert, in dry grasslands, on rockwalls, and rock crevices in elevations from 1200 to 1600 m. Blooms from May to July.
Description: Cactus of columnar habit, rarely branched and then only from base. Stem is erect, short, 6–18(–30) × 9–11 cm, usually with 18–23 ribs, areoles spaced 3–5 mm apart. Spines 15–23, straight or slightly curved, pectinate, gray to reddish brown or pink, no central spine. Flowers 6–8 cm across, tube 6–7 cm long, perianth pinkish-red to purple, stamens numerous, shorter than style, stigma green. Areoles on the ovary very spiny. Fruit globular, 3 cm, very spiny; seeds black, tuberculate, 1.5 mm.
Threat and protection: Protected by international trade agreement CITES.
Note: Genus Echinocereus contains about 45 species, most of them showy and all of them in the west of US and Mexico.
Echinocereus rigidissimus
Echinocereus rigidissimus
Echinocereus rigidissimus
These images were taken in USA, Arizona, Arivaca Area (May 2009).