While many succulent species might not be safe to handle, there are some that have healing and medicinal benefits you will want to keep close by. For example, the stem joints for both the cholla species and the prickly-pear cacti are very weak. You're sure to find pleasant surprises in the cacti family. Devil's head cactus is just one of the more than 1700 surprises (species). You can make the story even more interesting by adding rare, exotic species. At the end of the cold season, sow the seeds in a well-draining mixture.