The Devil's Claw-3
Having completely shed its gourd-like covering, and with its jaws set for a passing animal, it will be seen that the pod itself is covered with prickly spines. When the fish-hook points of the prongs bite into the leg of an animal, the whole contrivance becomes balanced from that point, and at each jolt and jounce the heavier body of the pod pounds down upon the leg, its spines causing great pain. There is an opening between the two prongs at the upper end of the pod itself from which the seeds come out at every bounce. When these are scattered over a mile or two of new environment, the pod falls apart.
This image is from: Luther Burbank: his methods and discoveries and their practical application. Volume 1 Chapter 3