athalamous

Century Dictionary and Cyclopedia

1. In botany, without apothecia: applied to lichens, or lichenoid growths, the fructification of which is unknown.

Wiktionary

1. adj. botany, rare Not furnished with shields or beds for the spores, like the thallus of certain lichens.

GNU Webster's 1913

1. adj. (Bot.) Not furnished with shields or beds for the spores, as the thallus of certain lichens.