African Milk Tree
The African Milk Tree is native to Central Africa. It is often grown as a hedge there, useful for its rapid and enthusiastic growth, though its roots are not invasive. Though it looks a lot like a cactus, it is actually a succulent plant. It has many folk names, including Candelabra Cactus, Cathedral Cactus, Friendship Cactus, Good Luck Plant, or Good Luck Cactus (the Good Luck attribution is probably due to how quickly it grows, and how easily it propagates). It stays lush and green throughout its growing season, and new growth has a lighter green colour than the base plant. The Rubra or Royal Red cultivar is very popular for its dramatic colouring: it takes on bright red accents later in the season.
The African Milk Tree is long-lived and can grow very vigorously, 1 to 2 feet a year in height, to a total of 8 feet tall. If grown indoors, it will grow to about half that height. They're grown by many gardeners in states with arid climates where the temperatures at night don't go below 50 degrees Fahrenheit, such as parts of Texas, Arkansas, and Arizona.