Oreocereus contains a small number of columnar cacti coming from high altitude areas of 3000 meters in the Andes Mountains of South-Americas Peru, Chile, Bolivia, and Argentina. They vary in shape from prostrate clusters to 3 meter tall columnar species. All the species are covered with an abundant hair like material that protects them from the sunlight, and probably also from abrupt temperature variations. The name Oreocereus comes from the Greek for ‘mountain Cereus’. Mature cacti produce showy light coloured flowers in summer. Oreocereus species are generally propagated from seeds. A number of Oreocereus species are found in cultivation, grown primarily for the dramatic white hairy stems and puts them all under the common name “Old Man Cactus” or “Old Woman Cactus”. Stems underneath are ribbed and notched between areoles. Some species in this genus have so much hair that it completely obscures the stems underneath. While the wooly covering gives them a soft appearance, closer examination reveals sharp spines extending beyond the wool. Oreocerues species are cold hardy to -12°C. They do well in raised garden beds, rockeries and large pots.

Oreocereus fossulatus is a native of Argentina, Bolivia and Peru. The common name, Old Man of the Andes, refers to the white “beard” that covers the plant and gives it a candy floss appearance, but beware of the sharp yellow thorns hidden within the abundant white hairs. It grows slowly to 3 meters in height and each stem can reach 11 cm in diameter. These cacti are very frost resistant. Oreocereus fossulatus bears eye-catching 7-10 cm flowers in summer. Like most other cacti they too form cresting growth from time to time.