[Wikipedia] Description: Like its cousin the jumping cholla, the stems detach easily, and the ground around a mature plant is often littered with scattered cholla balls and small plants starting where these balls have rooted. The "jumping" part of the name is said to have originated because a person who is walking in the desert can step on a grounded stem with the heel of a boot or a shoe, which can cause the stem to swivel up and embed spines in the walker's calf. (link added by Mary Ann Machi)