"Old Man Cactus" is a common name given to the cactus species Cephalocereus senilis. It is native to Mexico, where it grows in arid regions at elevations of up to 2,000 meters.
The plant gets its common name from its long, white hairs that cover its stem, giving it the appearance of an old man's beard. The hairs serve as a protective mechanism, helping to insulate the cactus from the hot sun and reduce water loss through evaporation.
Old Man Cactus can grow up to 10 meters in height, although it typically reaches heights of 3-6 meters in cultivation. The plant produces bright pink flowers in the summer, which give way to red or purple fruit.
In cultivation, Old Man Cactus is often grown as an ornamental plant. It is relatively easy to grow and care for, and it can be grown indoors or outdoors in a sunny, well-draining location. However, it should be noted that the plant has sharp spines and should be handled with care.