For more information on some of the best specific cacti and succulents, pick up a copy of Favorite Cacti for Indoors and Favorite Succulents for Indoors. To select a healthy cactus or succulent, look for a plant with good color. It should be in a pot large enough to provide the plant stability. Look for signs of recent growth and check to make sure it is firmly rooted. The word succulent simply means juicy and fleshy.
All succulents have the ability to store water in their flesh.
There are enough exceptions to that rule that it really isn't very useful. Holiday cacti are true cacti and they don't have any thorns. And on the other hand, many indoor plant growers have had to pull out the bandaids after dealing with their agaves, a type of succulents known for wicked spines. Cacti all belong to one family, Cactaceae. There are hundreds of varieties offering almost every imaginable shape and size.