Definition of "cryptogamic"

A number of cryptogamic plants swim about at random in the waters, among which the most interesting, perhaps, in our present state of knowledge, is the sargasso, or gulf-weed of voyagers (Fucus natans), which is found in the Gulph of Florida, and some other parts of the ocean floating in masses or fields, many miles in length.

1826, James L[awson] Drummond, “Of the Root (Radix)”, in First Steps to Botany, Intended as Popular Illustrations of the Science, Leading to Its Study as a Branch of General Education, 2nd edition, London: Printed for Longman, Rees, Orme, Brown, and Green, […], page 31