Cereus forbesii, from Bolivia and Argentina, recently has been lumped into Cereus validus, but the description does not remotely match these plants. For one thing, the typical species is a columnar cactus with 4-sided stems. The flowers are the typical Cereus form, large and white with purple hues. This species is hardy in Tucson with minimal damage at 15F. These plants are seedlings in one-gallon pots.