Old man cactus obviously got its common name from its striking appearance. Like an old man, it has white hair and a rather slow-paced growth.
This Mexican cactus is so thickly covered with soft-looking white hairs that its columnar stem is often entirely obscured. Don’t give in to the temptation of stroking its soft fur, though, as the dense fleece conceals some rather wicked spines. Very slow-growing, it can reach ceiling height, but only after many decades. Flowering is unlikely indoors.
To clean its fur, dip an old toothbrush in soapy water and give it a good shampoo.