Niebla, also known as the sea-fog lichens, is a genus of yellow-green fruticose lichens that grow on rocks, trees, and shrubs within the fog zone of coastal North America,[1] or more narrowly defined to occur on rocks and soil along the Pacific Coast from Mendocino County in California south to Baja California Sur.

[7] A second group that contains depsides but also includes the acid-deficient chemotype (N. homaleoides), collectively treats 32 species under the name N. homalea.

Molecular studies on the North American species of Niebla and Vermilacinia have been limited and contradictory.

[6] However, source material (voucher specimens) cited in the later study for the basis of the DNA analysis of Niebla was reported to be from California and identified N. homalea with protocetraric acid and triterpenes.

But this chemotype had not been known in Niebla, nor are depsidones known to be present in N. homalea, nor are they present in any species of Niebla in California;[2] protocetraric acid is found only in N. pulchribarbara, which lacks triterpenes, a rare species that occurs in northern Baja California.

Salazinic acid is a common lichen substance accessory to triterpenes in species of Vermilacinia, while it may also be noted that the morphology of V. laevigata is easily confused with that of N. homalea.

[2] The morphological characters employed to distinguish species of Niebla include the orientation of ridges in the lichen cortex,[9] differences in fragmentation branchlets, which often have black carbonized pycnidia, and the development of specialized asexual propagules referred to as soredia and isidia.

[2] Niebla is related to Ramalina and Vermilacinia, distinguished from them by the presence of thread-like hyphae intertwined into gelatinized cords called chondroid strands.