Polypodium quidem est herba similis filici i.e. polypodium is a plant resembling fern which grows on oaks, rocks, walls and stones. The best specie of it is that which grows on the oaks. Its root is best, and it is good while getting green. According to the Antidotarium it is called a knotty stick of the color of ashes, which becomes darker or redder. It is better growing red rather than yellow, and when it is firm, green, and fresh.
Nature: hot in the second degree and dry in the third degree. It purges phlegm primarily, and melancholia secondarily, without hurting or wounding.