Sadleria cyatheoides, commonly known as amaumau fern or amau, is a fern species in the family Blechnaceae.
Reaching a height of and a trunk diameter of , amau resembles a small tree fern.
The young fronds are often tinged red to block harmful sunlight.
It is endemic to Hawaii and inhabits lava flows, open areas, and wet forests on all major islands up to an altitude of .
Its pith and young fronds are edible either roasted or steamed.
Këlauea's Halemaûumaûu is named for this species.