POLARIZED AND SPECULAR REFLECTANCE VARIATION WITH LEAF SURFACE-FEATURES

The linearly polarized reflectance from a leaf depends on the characte ristics of the leaf surface. In the present study the leaf reflectance of a number of plant species with varying surface characteristics was measured at the Brewster angle with a polarization photometer having 5 visible and near-infrared wavelength bands. We found that all leaf s urfaces polarized incident light. Differences among species could be e xplained by variation in surface features. The results support our hyp othesis that the polarized light is reflected by the leaf surface, not by its interior. Two mechanisms appeared responsible for the linearly polarized reflectance: (1) specular reflectance and (2) surface parti cle scattering. In most cases, large values of linearly polarized refl ectance could be attributed to specular reflectance from the leaf surf ace. Attribution required knowledge of the optical dimensions of featu res on the leaf surface.