They are evergreen plants with plump fronds and bulky rhizomes that often protrude above-ground as a woody lump.

[2][3] Spleenworts have elongated, rather than circular, sori;[4] those of Asplenium obtustatum grow to 1 centimetre (0.39 in) long.

It is also reported from various southern Pacific and Atlantic islands and from parts of South America.

[5][6] Asplenium obtusatum is commonly known as the shore spleenwort; its Māori name is "paranako".

[6] There are two subspecies: A. o. obtusatum, more common in the South Island; and A. o. northlandicum, smaller and found near Auckland.