Modification of leaf morphology by heavy shade was determined for 27 hardwood species and related to shade tolerance. A ratio representing the effect of shade was obtained by dividing the thickness of palisade tissue, spongy mesophyll tissue and blade thickness in the sun leaf by the thickness of the corresponding tissue in the shade leaf. The species were arranged in a graph according to ascending order of palisade tissue ratios. The spongy mesophyll ratios and Baker's tolerances are also indicated by appropriate symbols. The spongy mesophyll tissue was much less reduced by shade and the ratios were too erratic to be related to tolerance of species. Total blade thickness of both sun and shade leaves was too variable to be related to tolerance.
Document Type: News
Professor of Silviculture, Univ. of Georgia, Athens