Echinocereus viridiflorus var. viridiflorus Engelm.
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.
2012 Kara Nursery