Cylindropuntia prolifera is a mostly erect, treelike cactus which can approach 3 meters in maximum height.

The gray-green segments are narrow and cylindrical, surfaced in fleshy tubercles bearing many brown or reddish spines up to 2 centimeters long.

The flowers are reddish purple and often borne on the fruits of previous seasons.

[1] In parts of Australia, Cylindropuntia prolifera could be used as a case study in invasive species.

While they don't seem to flower as prolifically as the literature might suggest, they spread by stem segments breaking off and travelling on the fur and feet of animals, at times crippling or killing them, or on car tyres.