The crossword solution for the term 'Plant Prickle' is BUR, which stands for a type of plant prickle called a burr. A burr is a seed or fruit with sharp hooks or spines that attach to clothing and fur, making it difficult to remove. They are commonly found on plants such as burdock, cocklebur, and sticktights. Burrs are also known as 'stickers' or 'hitchhikers' because of their ability to attach to animals and clothing.