Is acclimation required for success in high light environments? A case study using Mycelis muralis (L.) Dumort (Asteraceae).

In the field significant differences in maximum photosynthetic O -exchange rate (P ) were found between leaves of Mycelis muralis (L.) Dumort (Asteraceae) collected from woodland and exposed habitats, with the highest values in the exposed sites- However, there were no differences in the P of leaves collected from plants growing in grikes (fissures in the limestone pavement), of exposed limestone pavement, despite a greater than four-fold difference in the integrated daily irradiance. Leaves of plants from the open pavement had lower photon yields (ø ) and higher dark respiration rates and light compensation points, in comparison to shaded plants.