The Slipper Plant (Euphorbia lomelii, formerly Pedilanthus macrocarpus) is native to Sonora and the Baja California Peninsula in of northwestern Mexico. Its showy orange-red, zygomorphic cyathia are adapted for hummingbird pollination. It thrives with the standard succulent care of bright light and excellent drainage. It is frost tender, but I keep plants outside year-round under the eaves of a porch in USDA Zone 9b (down to 25º F/-4º C), where it receives little or no water in Winter.
Another common name for this plant is Candelilla, but don't confuse it with the Chihuahuan Candelilla (Euphorbia antisyphilitica), which has very different cyathia adapted for insect pollination, but can be grown under similar conditions