Echinocereus parkeri

Echinocereus parkeri grows in compact cushions or open groups with many shoots. The shoots, which are tapered or cylindrical, can reach up to 15 cm (5.9 in) in length and 2 to 6 cm (0.79 to 2.36 in) in diameter. They have six to ten tuberculated ribs. The one to eight central spines, initially dark but soon turning glassy white to yellowish, range from 2 to 6.5 cm (0.79 to 2.56 in) long. The six to 18 slender, mostly glassy radial spines are 0.7 to 1.2 cm (0.28 to 0.47 in) long. The funnel-shaped flowers are magenta to deep pink with a white throat. They appear near the tips of the shoots, measuring 4.5 to 5.5 cm (1.8 to 2.2 in) in length and 4.5 to 6 cm (1.8 to 2.4 in) in diameter. The green, spherical fruits have white flesh and are covered with falling, glassy white spines.

Echinocereus parkeri is found growing in the Chihuahuan Desert in the Mexican states of Nuevo León, Tamaulipas, San Luis Potosí, and Zacatecas at elevations of 1450 to 1900 meters. Plants are found growing among Mammillaria melanocentra subsp. rubrograndis and Mammillaria glassii.