Polypodium vulgare var. columbianum Polypodium vulgare var. perpusillum Polypodium prolongilobum Polypodium vulgare f. perpusillum Polypodium vulgare var. hesperium Polypodium vulgare subsp. columbianum
World Flora Online, http://www.worldfloraonline.org/, accessed June 20, 2024