CHARACTERIZATION OF PLANT EPIDERMAL LENS EFFECTS BY A SURFACE REPLICA TECHNIQUE

Optical replicas of leaf surfaces were made for characterizing the lens properties of individual epidermal cells. Using a dental latex, moulds were made of leaf surfaces and subsequently used to produce agarose replicas. The replicas focused light in a manner similar to intact epidermal cells and it was possible to measure both focal lengths and intensifications within leaf replicas of Thermopsis montana, Mahonia repens, and Smilacina stellata which had epidermal cells of different diameter. Focal lengths ranged from 74-130-mu-m which indicated that light was concentrated within the underlying photosynthetic tissues of these leaves. Focal intensifications were measured sensiometrically and were 1.5 for T. montana and 2.6 for the other species. These values compare favourably with calculated focal lengths and measurements taken from isolated epidermal layers. The results indicate that the epidermis can concentrate light within the leaf to amounts well in excess of ambient light. Furthermore, the replicas faithfully reproduced fine anatomical details from a wide variety of leaves and they provide a non-destructive way to reproduce surface characteristics for anatomical and physiological studies.