Most angiosperms, also known as flowering plants, propagate through seed dispersal. For the seeds to be able to disperse, the plant flowers and the seeds fall to the ground, are eaten and carried away, are blown by the wind or they are carried by a person or animal in the form of a bur. Many different types of plants have burrs, and they are all for seed dispersal purposes. This allows the seeds of the plant to travel far and wide and grow where they fall.
Examine the shape of the protrusions on the plant. The burrs on plants are a type of fruit with either an elongated or globular shape.
Observe if the protrusions on the plant have hooked spikes on them or not. The hooked spikes on burrs latch onto clothing and fur, much like Velcro.
Touch the plant burr with a piece of clothing. If it sticks to clothing, then it truly is a plant burr. If not, it might just be a furry plant fruit of some type.