Oreocereus trollii, commonly known as the Old Man of the Andes cactus, is a species of cacti native to Argentina and Bolivia.

[4] Slow growing, O. trollii produces red flowers, typically after reaching several feet in height.

[2] Oreocereus trollii grows with shoots that branch out from the base, forms small groups and reaches heights of up to 50 cm (20 in).

The short, columnar, light green shoots reach a diameter of 6 to 10 cm (2.4 to 3.9 in) and are densely wrapped in wool.

Oreocereus trollii is distributed in the Bolivian departments of Chuquisaca, Oruro, Potosí and Tarija and in the Argentine province of Jujuy in the puna vegetation at altitudes of 3000 to 4000 meters.