Phymatosorus scolopendria is a polypod fern native to tropical regions of the world. Its native range extends from tropical Africa to India, Thailand, Malaysia, the Philippines, Australia, Micronesia and Polynesia. It has also naturalized in Hawaii, Florida and Puerto Rico. Phymatosorus scolopendria typically grows in disturbed areas, secondary forests, and in coral rock crevices. At low elevations, it may be found amid scrub vegetation. It is often found growing as an epiphyte. In Hawaii, this fern is called laua’e haole; it is also known as wart fern, monarch fern, creeping fern, serpent fern, water fern, and maile-scented fern.
Wart fern can be recognized by its broad, glossy fronds with wart-like protuberances on the upper surfaces. Varying in length from 10 to 90cm, the fronds are divided into 1-10 pairs of lobes. These up-to 40cm (1.3 ft.) long lobes are entire and pinnately divided, with the longest lobes occurring near the base of each frond. The fronds of wart fern have a scent similar to that of maile (Alyxia oliviformis), which is akin to that of newly-mown hay. Round, reddish sori on the underside of each frond line the midrib in irregular rows. These sori are embedded into the body of the frond, producing visible bumps on the upper surface (the “warts”). Fronds are supported by glabrous stipes up to 50cm (>1.5 ft.)long which are sent up from scaly, dark brown rhizomes.
According to the CRC World Dictionary of Medicinal and Poisonous Plants: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology by Umberto Quattrocchi (CRC Press, 2012), the fronds of wart fern are pounded for use as treatment for boils and filariasis. Whole fronds are placed on beds so as to ward off bed bugs. In Pteridology in the New Millenium, edited by S. Chandra and M. Srivastava (Springer Science+Business Media Dordrecht, 2003), it is noted that wart fern contains coumarin, volatile oils, saponin, and glycyrrhizin . The fronds are sometimes used for flavouring or made into garlands.