Adenophorus periens is a rare species of fern known by the common name pendant kihi fern. It is endemic to Hawaii, where it is known from one population in Puna on the island of Hawaii and a few occurrences on Kauai and Molokai. The fern occurs in wet mountain forests on volcanic slopes. It grows on trees. There are perhaps 2000 individual plants remaining. This is a federally listed endangered species of the United States.