Although modern ranchers and wildlife managers often consider bracken ferns a nuisance, they may be utilized by humans in a variety of ways. In fact, they were so valued in the Middle Ages, when they were commonly used as a source of fuel and as a roofing material, that they could be used as a sort of currency. Bracken ferns were also widely used at one time in the production of potash and bleach, and continue to be utilized in some locales as a food source and as bedding for cattle. The rhizomes of the plants are especially useful. Their extracts can be used to dye wool and tan leather, their starch can be used as a type of flour, and they may even possess medicinal qualities, having been utilized both as a treatment for bronchitis and parasitic worm infections