The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
adder's-tongue fern
NOUN:
Any of various ferns in the genus Ophioglossum, having leaves divided into a simple, sterile blade and a slender, spikelike spore-bearing segment. Also called adder's-tongue.
ETYMOLOGY:
From the resemblance of the spike at the base of the frond to a snake's tongue.
