I have a number of small cacti I have recently been trying to identify. I've figured out all of them but these four. The first three were grouped together like that when I bought them at the nursery. I'm wondering if the flat padded one is Opuntia aciculata ("Old Man Whiskers"), but I'm not sure. As for the single newly planted cutting, I took it from a cluster of similarly shaped growths. Any guess as to the identify of these four cacti would be greatly appreciated.
The one in back on the first picture may be Stenocereus thurberi. (Disclaimer: I am not a cactus expert.)
S. thurberi seems correct. Most Opuntia are too hard to identify for me, and this is one of them. The third could be a Coryphantha, but I cannot see any furrows on the tubercles. The one in the second photo is a bit small, but I think it is a Mammillaria elongata.
Thanks a lot for your thoughts. I agree that the tall one and the single cutting look like S. thurberi and M. elongata, respectively. I looked at some pictures of Coryphantha, and I'm wondering if the short round one in the group could be C. cornifera (Rhinoceros Cactus)? It hasn't developed central spines, but that's normal for young ones, right? I'm attaching a close up. Maybe better detail will help.
Coryphantha are not easy either, not for me at least. Your plant resembles my own C. cornifera, so I think it is a possibility. I cannot see the typical grooves on the upper side of the tubercles, but I think they have something to do with flowers, so maybe they will appear later (distant memory, can be wrong).
