|Photos by Mark Hengesbaugh 5/5/2015|
Even chollas can form crests. This Chainfruit (aka Jumping) Cholla (Cylindropuntia fulgida var. fulgida or var. mammillata) is located on the path between the parking lot and the fence along Remount Rd.
As I've mentioned, there are various reasons for crest formation, but all crests form at a growing tip. Other plants form crests as well. Kim Gregory sent in this link about fasciation (cresting) that's fascinating : -) Thanks, Kim.