What are cryptogams?
In 1883, August W. Eichler, the prominent plant taxonomist of the day, divided the plant kingdom into two groups: Cryptogams and Phanerogams. Cryptogamae are seedless and have inconspicuous reproductive structures while Phanerogamae produce seeds and have visible reproductive structures (like flowers and cones). Cryptogamae means hidden reproduction, referring to the fact that no seed is produced. Instead reproduction occurs by spores. Eichler only classified plants as cryptogams but the definition has since expanded to include, among others, mushrooms and blue-green algae. This collective group, while taxonomically incoherent because it includes species from more than one Kingdom, represents the most ancient lineages of land-dwelling species on Earth.