Last year as I was leaving a cactus nursery, I saw a segment of Spruce Cone Cholla (Tephrocactus articulatus var. diadematus 'inermis') lying on the ground in the parking lot. It appeared to have been there for quite some time, as it was quite dehydrated and wrinkly. Obviously, it had come off someone’s purchase during transport to his or her vehicle. It was surprising that it hadn’t been flattened in the busy parking lot.
Since this form of T. articulatus doesn’t have any spines, (“inermis” derives from the Latin adjective meaning unarmed or spineless) I picked up the segment with my bare hands and took it home.Segments of T. articulatus easily separate from the main cactus and readily root, so I placed the segment in full sun, barely touching the soil under the landscape granite. Within two weeks, it had formed a bud and flowered. Although the segment sort of blends in with the gravel in the photo, it is easy to see that it was still in its dehydrated state. Dehydration does not stop flowering.
There are five species in the genus Tephrocactus, sometimes classified under the Opuntia genus. None of the five is frost sensitive. The T. articulatus species has several varieties in addition to the one described here. I wrote about one of those varieties in another post.