bifacial (adjective) – having two opposing surfaces that are alike but not identical (e. g., one side may be differently structured, coloured etc.). Attention: If the outer surface organization is reflected internally by a clearly layered anatomy the thallus may better be referred to as a foliose thallus with an erect (upright) growth, e. g., in Evernia. Many foliose lichen genera appear fruticose but their flattened lobes have a distinct upper cortex followed by an photobiont layer, medulla and lower cortex. The lower side thus has no photobiont layer and upper and lower cortex may have a different plectenchyma structure. In contrast, bifacial branches of fruticose lichens are internally more or less uniform.