Alsophila insulana, synonym Cyathea insulana, is a species of tree fern native to New Guinea, where it grows in mossy forest and ravines at an altitude of 750–1600 m. The trunk of this species is erect, 8–10 m tall, and 14 cm in diameter. Fronds may be bi- or tripinnate and approximately 3 m in length. They form a spreading crown. The stipe bears thick spines as well as scales. These scales are either small, pale brown, with a short fringe, or large and glossy brown, with fragile edges. Sori are borne near the fertile pinnule midvein. They are protected by thin, pale indusia.