Cylindropuntia bigelovii

A short, viciously-spined cholla, usually with a well-developed dark brown or blackish trunk. The joints break off readily and attach themselves to passers-by, hence the common name "jumping cholla". The larger Cylindropuntia fulgida is similar in habit but has persistent fruits.

Plant habit in the Phoenix Mountains Preserve northeast of Squaw Peak, 27 Dec 2007.