Flimsy thalli (from Albert Schneider's A text-book of general lichenology)
Some thalli have very little substance to them. These drawings show cross-sections through entire thalli. In all cases the darker, rounded cells are the photobiont cells which are amongst the filamentous hyphae.
1. Biatorina pineti 2. Arthonia radiata 3. Xylographa parallela (A wood-inhabiting species with the thallus often growing within the wood.)
Note: not all to the same scale.
Albert Schneider's A text-book of general lichenology, published in Binghamton in 1897 by Willard N. Clute & Co. illustrates the structural features of various lichens from the north-eastern United States.