CUTICLE MICROMORPHOLOGY OF AGATHIS SALISBURY

Cuticle micromorphology from all 21 species of the Southern Hemisphere conifer genus Agathis Salisbury was studied with scanning electron mi croscopy. External and internal features of abaxial and adaxial cuticl es are characterized for the three recognized sections of the genus. E xternal cuticle surfaces of all species are undulating and exhibit Flo r-in rings and stomatal plugs, with most species being hypostomatic. S unken stomata of various orientations occur in discontinuous rows and have three to nine subsidiary cells, four being the common number, and bilobed polar extensions. Epidermal cells are usually rectangular, bu t vary considerably even on one leaf. The cuticle on guard and subsidi ary cell surfaces is smooth to striated and pitted and can be useful i n identifying taxa. Distinguishing characters useful at the levels of genus, section, and species are outlined. Micromorphological features distinguishing Agathis from Araucaria include the undulating epidermal cell surfaces, the presence of Florin rings, stomatal orientations, a nd bilobed polar extensions. Subsidiary cell number, shape, and morpho logy and stomatal orientations are the best characters to use when dis tinguishing fossil araucarian cuticles from those of broad-leaved podo carps.