It is easily confused with the related Dryopteris dilatata (broad buckler fern), differing in the usually smaller fronds, and in the pale brown scales on the frond stem being more uniform in color, rarely having a dark central stripe.

[4] Dryopteris expansa was given its first scientific description in 1825 by Carl Borivoj Presl in 1825, who named it Nephrodium expansum.

[6] However, the type locations in that work cannot be relied upon due to mistakes made when the specimens were originally collected or during the long storage before being examined by Presl.

The specimens were collected by Thaddäus Haenke during his long travels and sent back to Europe where they sat unregarded for at least 25 years until they were acquired by the Bohemian National Museum at Prague in 1821 and were finally examined in detail.

The root contains filicin, a substance that paralyses tapeworms and other internal parasites[medical citation needed] and has been used in herbal medicine as a worm expellent.