Flowering plants noted for their spined stems and leaves, and their bright purple flowers. In Middle-earth, they are generally associated with the lands around the Shire, though doubtless they grew further afield. In particular, they are noted as growing thickly in the Bonfire Glade within the Old Forest. A little to the west of that forest, within the Shire itself, the Thistle Brook that flowed into Willowbottom took its name from these plants.