''Asplenium unisorum'', the singlesorus island spleenwort, is a species of fern endemic to the

Hawaiian Islands The Hawaiian Islands () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...

. It only lives between 650 and 700 m in the Wai'anae Mountains on the island of O'ahu. It is classified as critically endangered, with a fragmented, actively shrinking mature population of around 1,148.

Description

It grows 0.5-3.0cm tall, with a 0.5-1.0cm diameter. Leaf stalks branch off the main stem, which also features a few "small black scales". The stalks themselves are "black and shiny", around 2.0-5.0cm long. Branching off from the stalks, the fronds of the fern are 8.0-30.0cm tall by 0.5-3.0cm broad.

References

unisorum Plants described in 1951 Endemic flora of Hawaii Native ferns of Hawaii {{Polypodiales-stub