Cuticular Features and Epidermal Patterns in the Genus Araucaria de Jussieu

Abstract

The cuticular organization and epidermal features of leaves from the four sections of the genus Araucaria, growing under similar environmental conditions, were studied by scanning electron microscopy. Cuticles from these extant species and the Jurassic fossil Araucarites santaecrucis were compared by rubber replicas and examination of the fossil leaf surfaces. Two distinct groups of araucarian leaves are distinguished by cuticular features. The Columbea-Bunya species have regular stomatal rows with polar cells always oriented in the same direction, four to five subsidiary cells, and a granular inner cuticle surface on both epidermal and subsidiary cells. The Eutacta-Intermedia species have four to seven subsidiary cells with thin cuticular flanges between guard cells and subsidiary cells, a smooth inner cuticular surface on both epidermal and subsidiary cells, and thinner intercellular flanges on epidermal cell walls. Epidermal features of araucarian leaves appear to be taxonomically useful at the section level.