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Any of various ferns in the genus Ophioglossum, having an erect stem that branches into a single oval blade and a spikelike spore-bearing stalk. Also called adder's-tongue.
[From the resemblance of the spike at the base of the frond to a snake's tongue.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.