Thallogen

Thal´lo`gen


n.1.(Bot.) One of a large class or division of the vegetable kingdom, which includes those flowerless plants, such as fungi, algæ, and lichens, that consist of a thallus only, composed of cellular tissue, or of a congeries of cells, or even of separate cells, and never show a distinction into root, stem, and leaf.
Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.