Echinocereus viridiflorus is an evergreen cactus / succulent with green foliage. In spring and summer chartreuse flowers emerge. Grows well with sun and low water. Does well in well-drained soil. A good option if you're seeking something verticillium wilt resistant.
Very hardy. These are from colorful-spined plants which grow in Northern Colorado. Small growing. This species is widespread and is found in South Dakota, Wyoming, Colorado, Kansas, New Mexico, Oklahoma and Texas. The parents for these are from Northern Colorado, almost into Wyoming, where it's very cold and may be covered in snow much of the winter. They're extremely hardy, handling temperatures as low as -20 °F if kept dry.