Cylindropuntia imbricata cholla
(This plant comes in a 3.5" pot. You will receive a very similar plant to the one in the picture. It may or may not be blooming at the time of your purchase. The plant is shipped in its pot to prevent any damage to the roots).
Description: The cane cholla or tree cholla is a shrubby or even tree-like size cactus, its silhouette, and its long-lasting yellowish fruits. The above-ground part consists of of a number of succulent, cylindrical segments (joints) about 2-3 cm in diameter. These segments grow mostly end to end. Long spines possess papery detachable sheath. Leaves occur at the base of are-oles and are usually not seen on mature segments as they are shed early. A typical height is about 1 m, but exceptionally it can grow to 4.6 m with a "trunk" diameter of 25 cm. Flowers vary through shades or dark pink and purple with a boss of yellow stamens and bright white stigmas, and is said to be a shy bloomer until it reaches 60 cm tall. This plant may 20 years or more when well pleased with its environment.
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz