cryptogam

Concise Oxford English Dictionary © 2008 Oxford University Press:
cryptogam /ˈkrɪptə(ʊ)gam/

▶noun Botany, dated a plant with no true flowers or seeds, such as a fern, moss, liverwort, lichen, alga, or fungus.

– derivatives
cryptogamous adjective.

– origin C19: from Fr. cryptogame, from mod. L. cryptogamae (plantae) from Gk kruptos ‘hidden’ + gamos ‘marriage’ (because the means of reproduction was not apparent).