How do hooked fruits such as burdock attach to animal fur?

Hooked fruits, such as those of burdock, utilize a process known as epizoochory, which is the inadvertent transport of plant dispersal units by animals.12

In the case of burdock, the protective bracts surrounding the developing flower head—collectively called the involucre—are equipped with stiff, hooked structures. When an animal brushes against the plant, these hooks cling tenaciously to the animal's fur or to clothing. The entire hooked head is then carried by the animal until it is eventually dislodged, effectively dispersing the seeds far from the parent plant. This ingenious natural mechanism is famously cited as the inspiration for the invention of Velcro, which mimics the way these tiny hooks attach to loops of fiber.3124