The Ultrastructure of Lichens V. Hydrothyria Venosa, a Freshwater Lichen

Summary The fine structure of the aquatic lichen Hydrothyria venosa was investigated from collections made in the summer and fall. The phycobiont lacked plastoglobuli in the summer but did contain them in the fall. Polyglucoside granules, structures not found previously in lichenized blue‐green algae, were present in the phycobiont. The mycobiont lacked ellipsoidal bodies, structures that have been found in almost all previously studied lichen fungi.