With the exception of four counties along the west slope of the Sierra Nevada, Ramalina menziesii Tayl. is restricted in California to a coastal zone influenced by maritime conditions of fog or high humidity. Apparently the species is poorly adapted for survival in areas with extended periods of desiccation. It is hypothesized that the observed thallus water content during the early morning hours is sufficient to maintain low levels of photosynthesis for 2-3 hours. Morphological variations in R. menziesii indicate that the reticulate structure has an adaptational value in increasing water holding capacity of the thallus. Ramalina menziesii Tayl. (= R. reticulata (Noedh.) Kremp.) occurs abundantly from southeastern Alaska to central Baja California, primarily restricted to a narrow coastal zone. Typical substrates include Abies grandis and other conifers in the Pacific Northwest, Quercus lobata and Q. douglasii in central California, and such xerophytic desert species as Idria columnaris and Pachycormus discolor in Baja California. Despite many unique qualities, the biology of R. menziesii has been essentially ignored. The present study reports on investigations into the general ecology of R. menziesii and the interaction of morphology with habitat selection in determining the distribution and occurrence of this species in California. Within California, R. menziesii occurs irregularly in a band along the entire coast from Oregon to Baja California (Fig. 1). In addition, it occurs on many of the California Channel Islands. Although R. menziesii is generally considered to be restricted to the immediate fog belt along the coast, the greatest concentrations of this lichen often occur inland from this zone. This fact is particularly clear in central California where the species reaches its greatest development. Although not previously reported from there in the literature, R. menziesii occurs commonly in four counties along the west slope of the Sierra Nevada, an anomalous distribution for a coastal species. These localities in the foothills of the Sierra Nevada are well removed from any direct influence from maritime conditions. In order to investigate the ecological relationships of R. menziesii, field observations were supplemented by measurements of microenvironmental conditions existing in the lichen habitat. Summer periods of drought and high temperature in California represent a great potential physiological stress to large fruticose lichens because of their effect on the water relations of such species. Microenvironmental conditions during 'I thank Dr. Mason Hale for data on collections in the Smithsonian Institution. 2 Department of Population and Environmental Biology, University of California, Irvine, California 92664. This content downloaded from 164.67.185.251 on Tue, 19 Aug 2014 18:58:42 UTC All use subject to JSTOR Terms and Conditions 24 THE BRYOLOGIST [Volume 77 124 123 122 121 120 11 ls Il b r