The Pedilanthus macrocarpus, commonly known as Lady Slipper, is a slow growing plant that is part of a small genus within the Euphorbiaceae family. It is heat and drought tolerant, making it an ideal succulent for Arizona's low desert.
When planted among globular and pad-stemmed cacti, its pipelike stems and lime green color well-complement the various shapes of cacti and other succulents. It looks especially nice planted in linear groupings. It is also looks good and does well in pots.
The P. macrocarpus can take full sun, however, in full sun the stems can change from their characteristic lime green color to a yellow. They do best in dappled shade. When planted in full sun, the stems remain upright; in shade the stems arch and curve, actually adding even more interesting contrast to surrounding plants. In the summer, red cyathia, supposedly shaped like a lady's slipper, appear on the stems. (I've looked at the cyathia from every angle and I just don't see any slipper resemblance!) Hummingbirds love the cyathia.
Although ideal for our climate, the Lady Slipper is not readily available in local nurseries, and when it is, it is a bit expensive. I was able to get only one plant a couple of years ago, but the two nurseries I frequent never have it in stock when I'm shopping for more. When a plant does well in our climate zone, it amazes me that the nurseries understock it, while they always seem to have dozens of plants that are very inappropriate for the desert. Those plants don't have a chance in hell of making it planted in the garden, and usually will not make it as houseplants because of the extremely low humidity. Someone must be buying them. I guess there's a sucker born every minute.