Tmesipteris elongata is a fern ally that typically grows as an epiphyte (perched on another plant, which is usually a tree fern). The aerial stems are pendulous, with leaves spirally arranged. The leaves are 0.4–1.6 in (1–4 cm) long. The spore containing capsules are found on the stems.
Tmesipteris elongata is a primitive plant with a longer fossil history than a fern. It is found in lowland to montane forests, in North, South and Stewart Island, and the Chatham Islands, New Zealand.