Plant Description
Has 5 to 20 mostly erect stems in loose clumps. Spines not dense enough to obscure the stem.
Each spine cluster has 1 - 4 central spines pointing outward and upward. E. fendleri has fewer and shorter central spines. E. engelmannii central spines point upward.
Habitat
Sonoran Desert, flats to steep canyon sides, desert scrub, semi-desert grasslands, interior chaparral.
Flowers
Has large flowers with petals and sepals from 2-1/3 inches to 3-1/3 inches in diameter with a darker mid-stripe, Tips are relatively thin and delicate. Green stigmas and yellow anthers.
Stems
Mostly erect, diameter of 1-3/4 to 3 inches, 10 to 15 ribs with wavy forms.
Areoles
These are structures unique to cacti, found on the stems, areas from which spines, flowers and fruits emerge.
Spines are usually straight. Has conspicuous principal central spine 1 to 3 inches long. Radial spines are 1/2 inch to almost 3/4 inch long.
Fruit
About 1-3/16 inches long and 5/8 inch to 1 inch in diameter.