Low-magnification photographs of glabrous upper surfaces using white light show that no matter whether the visual appearance is shiny or matte, the outer cuticles are specularly reflective. In all cases, the individual epidermal cells are seen as bright spots of reflected light, due to their convex outer surfaces. This shows that at least some of the apparently diffuse reflection from leaves is specularly reflected from the outer surface. Quantitative data were obtained for both upper and lower surfaces of a variety of leaves, using light of 632.8 nm incident at 60° from the normal. Light departing the leafwas detected in two directions: normal to the leaf("diffiuse"), and at 60° ("specular"), and compared with the reflection from a standard white block. By this criterion, some leaves were quite shiny, confirming the visual impression, but others were not. In only two cases did the "diffuse" reflection exceed the "specular" (as would be expected from a true difluse reflector); these were leaves with thick coatings of hairs. Less than 10% of the incident light is reflected by the cuticle of a glabrous leaf. PLANT ANATOMISTS AND PHYSIOLOGISTS have long speculated on the relationship between the anatomy of green leaves and their physiological and ecological functions. Some roles have been recognized a long time, others only more recently. The role of a particular feature is not always obvious. Among the physiological roles of leaf anatomy may be: promotion of photosynthetic biochemistry (C-4 photosynthesis), solute and water transport, prevention of water loss, and adaptations to facilitate light absorption or rejection (by reflection or transmission) in an efficient manner. It is the latter feature toward which this research is aimed. It is important not only with respect to the basic photosynthetic function ofthe leaf, but presumably also with respect to the heat load and water relations of the leaf. In addition, the interpretation of remote sensing data depends upon leaf reflectance properties. In this report the reflective properties of the outer epidermal surface of the leaf will be examined, since this is the first surface encountered. The epidermis can interact with the incoming light in several ways: reflection, refraction, diffraction, and scattering. The external epidermal surface is obviously shiny in some species, and Haberlandt ( 19 14) considered this a significant function of the epidermis, reduc
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