(Photograph = Escobaria missouriensis, Kerry Woods)
Introduction
Many cactus names change over time. Sometimes whole genera are subsumed into (folded into) another genus. The result is that cactus names are sometimes hard to know and may depend upon which botanist you speak to or which magazine/book you read.
The Details
Coryphantha and Escobaria are similar genera. Probably they cannot be told apart unless you examine the seeds. The result is that some use the names interchangeably. For instance, Escobaria vivipara and Coryphantha vivipara both refer to the same species. Despite confusion, plants of either genus are formally recognized by most botanists as belonging to one genus or the other (New Cactus Lexicon), and you can look up the correct name there.
Escobaria are small cacti of the West and Mexico. They form small globes, columns, or even clumps of a few or many stems. The plants often have brilliant flowers, but may have tan or cream-colored flowers depending upon the species.
Escobaria are easy plants to grow in pots because they tolerate a variety of conditions if provided some sun and well-drained soil. Many Escobaria plants are cold hardy.
Additional Reading: Pincusion Cacti