There are a number of synonyms for the term "adder's-tongue," many of which refer to plants or flowers that have a similar appearance or characteristics to the adder's-tongue fern. Some synonyms for adder's-tongue include the Grammitis genus of ferns, which also have a similar growth pattern and leaf shape to the adder's-tongue. Other synonyms include the Ophioglossum genus of plants, which are commonly known as "adder's-mouth" due to their similarly shaped leaves. Additional synonyms include the yellow adder's-tongue, which is a type of wildflower commonly found in North America, and the smooth adder's-tongue, a type of fern found in Europe.
