LEAF SURFACE-MORPHOLOGY OF ERYTHROXYLUM SP AND DROPLET SPREAD

Studies were conducted to examine the micromorphology of leaf surfaces of coca and nova plants and to determine which spray diluents provide d optimum coverage of leaf surfaces. Adaxial leaf surfaces of both spe cies were covered with a smooth layer of polygonal-shaped epidermal ce lls which were covered with wax crystals. Abaxial leaf surfaces were c omposed only of papillae cells and the guard and subsidiary cells surr ounding stomata. Abaxial leaf surfaces of both species were also cover ed with wax crystals. Average wax weights were 28 to 53 mug CM-2. Wate r droplets containing an organosilicone surfactant at 0.1% by vol spre ad better on leaf surfaces that did other adjuvants. Droplets of sever al different petroleum-based oils spread much better on leaf surfaces than either water droplets with adjuvants or droplets of soybean or co ttonseed oil.