Morphological and physiological differences between epilithic and epiphytic populations of the lichen Parmelia pastillifera
1995
Tretiach, M. | Brown, D.H.
CO2 exchanges, morphology and chlorophyll content of epiphytic and epilithic populations of Parmelia pastillifera growing in the same locality (Bristol, UK) were investigated. Epilithic samples had reduced net photosynthetic rates and a lower chlorophyll content, apparently caused by the high levels of irradiance of the exposed habitat, not completely buffered by the increased thickness of the upper cortex. These samples also had much more developed rhizinae; this modification is interpreted as a mechanism to increase the water storage capacity of the thallus. Physiological differences between the two populations seem to be due to the more extreme environmental conditions of the epilithic population.
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