ECOPHYSIOLOGICAL STUDIES OF THE LICHEN, PARMELIA PRAESIGNIS Nyl.

S ummary Losses in photosynthetic ability were observed in the lichen, Parmelia praesignis Nyl., over a 2‐week period under three out of four different combinations of temperature and hydration conditions during storage. At a constant daytime temperature of 16 °C, lichens which were wetted even, few days retained more photosynthetic ability than did lichens wetted everyday. Lichens which were maintained under a varying range of temperatures (12 to 26 °C) retained most of their photosynthetic ability, with the material wetted daily eventually losing 40% of its ability. The material wetted every few days did not lose a significant amount of photosynthetic ability. Lichen material maintained at a temperature of 33 °C and wetted everyday lost all photosynthetic ability after 3 d. Photosynthetic ability was found to be normally distributed with a mean of 3.2 mg CO 2 g −1 and a standard deviation of 0.65 mg CO 2 g −1 h −1 when based on the experimental results from 25 randomly selected sets of thallus tips.