Botanical name: Euphorbia Tirucalli
Common name: Pencil cactus
Plant type: Cactus houseplant
Mature size: 6 feet tall
Sun exposure: Bright, filtered sunlight
Soil type: Gritty, well-draining
Another common name for the pencil cactus is milkbush because of the milky white, irritating sap the plant releases when the stems are broken. Though it is a succulent and not a true cactus, Pencil is an excellent cactus houseplant that provides a distinctive shape within an indoor landscape.