Echinocereus viridiflorus
Echinocereus viridiflorus is a species of cactus known by the common names nylon hedgehog cactus, green pitaya, and small-flowered hedgehog cactus. It is native to the central and south-central United States and northern Mexico, where it can be found in varied habitat types, including desert scrub, woodlands, dry grasslands, and short-grass prairie.
Description
This cactus has a small spherical to ovoid, sometimes elongated or cylindrical in shape, stem to over tall and up to wide. The 6 to 18 ribs are clearly humps. It is mostly unbranched but it may occur in squat clusters of several branches. The body of the plant is ridged and lined with many areoles bearing [Thorns, Thorns, spines, and prickles|spines, and prickles|spines]. The spines may be red, yellow, white, purplish, or bicolored, sometimes with darker tips and are up to long. The 8 to 24 marginal spines are also red, cream or brown and up to long. The flower is up to long and has tepals in shades of yellowish, brownish, greenish, or occasionally red, with darker reddish midstripes. The tepals are thin at the tips. They are usually wide open, funnel-shaped and green to yellow-green. They are long and large in diameter. The fruits are spherical, green and heavily thorny.Taxonomy
The species is most closely related to E. chloranthus Haage and E. russanthus Weniger. These species share small seeds, basal nectaral tissue, and flowers that are yellow/brown and less than 4 cm in length.The taxonomy within the species is uncertain, with authors recognizing several varieties which are sometimes treated as separate species. New molecular evidence suggests that E. viridiflorus subsp. cylindricus should be recognized as a distinct species because it has different morphology and different numbers of molecular autapomorphies than E. viridiflorus.
One variety, var. davisii, Davis' green pitaya, is federally listed as an endangered species. This taxon is very small, reaching no more than 3 centimeters tall. It becomes smaller when water is scarce, withdrawing under the ground, sometimes leaving just some spines sticking out.