Hymenophyllum australe, commonly known as austral filmy fern, is a relatively large and epiphytic fern, indigenous to eastern Australia and New Zealand. It belongs to the unique Hymenophyllum genus (filmy ferns), which are characterised by their thin membranous fronds that are seldom more than one cell thick, with the exception of regions over and around veins. Hymenophyllum australe is distinctive in that the fronds are typically thicker than other Hymenophyllum species, often being up to 2-3 cells thick.