The pencil cactus gets its name from its thin pencil-like stems that can grow up to 30 feet tall in the wild. These stems are green in color and can have a slight red tint in direct sunlight. The plant produces tiny inconspicuous flowers which are surrounded by small yellow or red bracts.
The pencil cactus prefers full sun and well-draining soil. It is drought-tolerant and can survive extended periods without water. Overwatering can damage the plant so it is best to let the soil dry out between watering. 
Disclaimer - plant will come in basic nursery black pot. The image is for representative purpose only, real plant may vary depending on growth conditions.