What is a plant of the highest class of cryptograms, including the ferns, etc. See Cryptogamia. The Age of Acrogens (Geol.), the age of coal plants, or the carboniferous era called?

acrogen — A plant of the highest class of cryptograms, including the ferns, etc. See Cryptogamia. The Age of Acrogens (Geol.), the age of coal plants, or the carboniferous era. (Webster's 1913.)

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