About Echinocereus viridiflorus Engelm.
Echinocereus viridiflorus Engelm. is a small cactus that typically grows as a single unbranched stem, though it may occasionally form low, clustered clumps of several branches. Stems range in shape from spherical to ovoid, and sometimes become elongated or cylindrical, measuring between 3 cm (1.2 in) and over 30 cm (12 in) tall, with a width of 1 to 9 cm (0.39 to 3.54 in). The stem has 6 to 18 distinct, bumpy ribs, and its ridged surface is covered in many areoles that produce spines. Longer central spines can be red, yellow, white, purplish, or bicolored, often with darker tips, and reach up to 2.5 cm (0.98 in) long. There are also 8 to 24 shorter marginal spines, which may be red, cream, or brown and grow up to 1.8 cm (0.71 in) long. Flowers of this species are funnel-shaped, usually open wide, and green to yellow-green in overall color. They grow up to 3 cm (1.2 in) long, and are 2.5 to 3.0 cm (0.98 to 1.18 in) long with a large diameter. Tepals come in shades of yellowish, brownish, greenish, or occasionally red, with darker reddish midstripes, and have thin tips. The fruits are spherical, green, and covered in many sharp thorns. The species is widespread across the U.S. states of South Dakota, Wyoming, Colorado, Kansas, New Mexico, Oklahoma, and Texas, and also occurs in the adjacent Mexican states of Coahuila and Chihuahua. One rare variety of this cactus has yellow-green flowers, and is endemic to Brewster County, Texas. This rare variety grows among Selaginella beds in rocky novaculite-derived soils. As of 1984, only one population of this rare variety was known, and its range is not expected to expand because it is restricted to this specific mineral substrate.
