This origin of this cactus is unknown, but it has apparently been present in this granite barren opening for a long time. While there is currently a bit of "rock gardening" happening around it, it was not planted by the current landowner. It was also not planted by the previous landowner, who reported that this had been present as long as they had the property, since the 1930s. This means this cactus has had a self-sustaining occupation of this outcrop for at least 80 years. Some pine needles have blown in, but there is also quite an accumulation of shed spines if you look closely.
Lepidoptera caterpillar attacking the cactus
Growing in a more or less wild front yard, by the fence.