May 16 2019
The Kauai Digit Fern, or Doryopteris angelica, is a rare fern found in the forest on the Hawaiian island of Kauai. Island species are some of the most rare and endangered in the world. Living on an island and evolving in isolation means they are often endemic, they don't exist anywhere else. Another result of that isolation is they often can't compete with invasive animal and plant species that have been introduced to an island's ecology. Kauai Digit Fern was first described in 1999 and just eleven years later it was federally listed as endangered. According to the IUCN Red List 2015 assessment of this fern there were just 250 mature individuals left, with a decreasing population trend. Some factors that threaten this fern include habitat degradation by humans, predation by introduced feral ungulates such as deer and pigs, and competition from invasive plant species introduced to Kauai from other parts of the world, including Lantana camara (native to American tropics), the grass Melinis minutiflora (native to Africa), and the tree Grevillea robusta (native to Australia).
