Complex sentence: The stems (cladodes) are composed of strongly flattened segments, which have two or three "teeth" of varying shapes along their edges and more at the ends, which are "cut off" (truncated) rather than pointed.
Split into simpler sentences: The stems (cladodes) are composed of strongly flattened segments, which have two or three "teeth" of varying shapes along their edges and at the ends. The ends of the stems are "cut off" (truncated) rather than pointed.