A COMPARISON OF LEAF PHYSIOLOGY AND ANATOMY OF QUERCUS (SECTION ERYTHROBALANUS-FAGACEAE) SPECIES IN DIFFERENT LIGHT ENVIRONMENTS

Physiological and anatomical attributes of leaves were examined of three species of Quercus section Erythrobalanus. All three species occur in moist temperate deciduous forests of eastern North America. Seedlings of each species were grown in different light conditions for comparison. The attributes measured were net photosynthesis, stomatal conductivity, blade and cuticle thickness, stomatal density, thickness of upper and lower epidermis, and thickness of palisade mesophyll. The results generally demonstrate the close association between anatomical adaptations and efficiency of physiological processes; they also elucidate the distribution patterns of the three Quercus species across the forest topography in southern New England. The most drought-tolerant and light-demanding species, Q. velutina (Lam.), exhibited the greatest leaf anatomical plasticity, the highest net photosynthesis in the different light conditions, and the lowest stomatal area per unit area of leaf. The most drought-intolerant species, Q. rubra (L.), exhibited the least leaf anatomical plasticity, the lowest net photosynthesis in the different light conditions, and the highest stomatal area per unit area of leaf. Quercus coccinea (Muenchh.) usually exhibited values that were intermediate between Q. rubra and e. velutina.