Rock Bushy Lichen

Ramalina intermedia is a fruticose lichen with slender, branched thalli that are primarily attached to a substrate, often trees or rocks, by a small holdfast. Its branches are flattened, sometimes twisted, and have a light greenish-yellow color due to the presence of usnic acid, which is a secondary metabolite common in many lichens. The surface of the thallus is typically covered in tiny, granular structures known as soredia, which serve as a means of asexual reproduction. These soredia are particularly concentrated at the tips of the branches, forming soralia—powdery patches that appear terminally on recurved lobe tips. Chemically, R. intermedia contains sekikaic acid and homosekikaic acid, with the occasional presence of atranorin, another lichen product. Thin-layer chromatography has confirmed these compounds across various populations, although there can be variations in their concentrations. The overall structure of R. intermedia is typically isotomic, meaning the branches are of more or less equal length, giving it a symmetrically branched appearance. However, adventive branching may occur after damage to the thallus, leading to irregular branch patterns. Microscopically, the photobiont layer—where the symbiotic algae reside—is located beneath a protective upper cortex, allowing the lichen to photosynthesize efficiently. …