Pencil Cactus (aka Euphorbia tirucalli) is not a cactus. It is a rugged succulent plant that can grow to be over thirty feet high in the wild. However, it can also be kept to a more moderate height of 6′-8′ feet when kept as a houseplant.
These attractive, interesting and beautiful fire stick succulent plants take on a great deal of character as they age, and older plants develop thick inner branches with rough, gray, highly textured bark. The foliage is an attractive shade of green throughout most of the year and transitions to yellow, orange or red during the cooler months. The plant originates in South Africa and India and has a lot of common names including Rubber-hedge euphorbia (Eng.), Kraalmelkbos (Africa.), Indiantree spurge, Firestick Cactus, Pencil Cactus, Sticks on fire, Pencil plant, Finger Tree, Naked lady, Red Pencil tree, Milk bush, ET. Euphorbia tirucalli produces small yellowish flowers that attract butterflies, bees and other insects. Euphorbia tirucalli flowers grow in clusters in the apex or angle of the branches during the cooler months of the year.