Blechnum filiforme or thread fern (pānoko in Māori) is an endemic New Zealand fern species in the hard fern family, Blechnaceae. The species authority is (A. Cunn.) Ettingsh. Thread fern has a creeping and climbing habit. It has three different types of fronds: long climbing fronds with long pointed leaves, shorter creeping fronds with nearly round leaves, and fertile fronds with threadlike leaves that give the species its common name.