Cereus — 8 species

Cereus is a genus of tall, ribbed columnar cacti native to South America, including the statuesque Peruvian Apple Cactus and Mandacaru. They thrive in full sun — a south-facing window within a foot of the glass is ideal indoors — and follow the classic cactus watering rule: soak thoroughly, then let the soil dry completely before watering again, roughly every two weeks in the growing season. Toxicity varies among species in this genus, so verify the specific species before buying if you have cats or dogs.