Morphological Variation and Development in Ramalina Menziesii Tayl.

Abstract

The common west coast lichen Ramalina menziesii Tay!. has been studied in an attempt to determine the extent of morphological variation and to understand the factors that determine its form. An analysis of a typical population near Santa Barbara, CA, suggested that intrapopulation variation in form was controlled primarily by size increase during growth. Test populations obtained from latitudes as far north as 54°N and as far south as 28°N had values for various morphological characters that were very similar to the Santa Barbara population. It is concluded that variation in form may be the result of differential rates of growth and possibly varying frequency of environmental stresses which disintegrate the thallus.

SALT LOADING DOES NOT CONTROL CO2 EXCHANGE IN RAMALINA MENZIESII TAYL.

“…was collected in July, 1984 from six locations in central California (Table 1), two of which (Hastings and Point Lobos) had been used in previous studies (Matthes-Sears et al, 1986a, b). At the three inland sites, R. menziesii occurred in its coarse, heavily netted morphological form, whereas the three coastal sites supported a more finely branched, less netted morphotype (Larson, 1983). Abundance and morphology of R. menziesii were shown earlier to be independent of the species of substrate tree (Larson et al, 1985).…”

“…He found that some of the mortality after NaCl treatments seemed to be due to a physical breakdown of salt-encrusted thalli coupled with a local desiccation effect. In an analogous way, microscopic salt crusts on developing net buds (Larson, 1983) could contribute to the early break-up of reticulations that distinguishes the coastal from the inland morphology.…”

Environmental variables controlling the uptake of carbonyl sulfide by lichens

“…Its reticulate thallus (i.e., the body of the thallophytes, which does not have roots and/or leafs) dominates the epiphytic community of central coastal California with a few stands as far east as the Sierra Nevada, often forming a dense, pendulous canopy . The thallus morphology ranges from relatively coarse nets in sunny, inland areas to thin filaments in foggy, coastal regions [Larson, 1983;Larson et al, 1985;Rundel, 1974]. Lichen samples were collected in the Hastings Natural History Reservation in Monterey County, at a rural site in central coastal California (36ø23'N, 121ø33'W; 490 m above sea level (asl)).…”

Reiterative production and deformation of cell walls in expanding thallus nets of the lichen ramalina menziesii (Lecanorales, Ascomycetes)

“…Both mechanical stresses (Lutz, 1894; Peirce, 1898) and programmed cell necrosis (Larson, 1983) have been proposed as mechanisms underlying perforation formation. Both mechanical stresses (Lutz, 1894; Peirce, 1898) and programmed cell necrosis (Larson, 1983) have been proposed as mechanisms underlying perforation formation.…”

“…This phenomenon is apparently related to its characteristic pattern of diffuse growth. Moreover, expansion of Ramalina menziesii reticula appears to be potentially indeterminate; Larson (1983), for example, found a 45-cm fragment with four remaining perfora-tions, and calculated the theoretical size of the entire net to be =11 m long. While morphogenesis of new perforated tissue in R. menziesii is localized at the net apex, tissue expansion occurs throughout the reticulum rather than being restricted to a specific zone of growth (Sanders, 1989(Sanders, , 1992.…”