Micromorphology of the leaf structures of Photinia davidiana (Rosaceae)

The morphological characteristics of the leaf blade of Photinia davidiana were analysed using digital light microscopy, scanning electron microscopy and confocal microscopy. Plants from different geographical origins were studied. The results showed low variability in all samples. Young leaves had burgundy-coloured stipule bases, petioles, midribs and leaf margins. The petiole is covered with dense trichomes, the leaf margin is rolled, the midribs and lateral veins on both sides of the blade are pubescent with short trichomes. The apices of the leaf blades and of the stipules end in colleters. The upper side of the blade has well-developed cuticular folds and the epidermal cells are cuboid with straight lateral walls. The leaves are hypostomatous and the stomata are round, measuring 24 × 20 µm. Stomatal dimorphism is well expressed in the larger primary stomata, with radial cuticular folds clearly visible. Differences between the evergreen Photinia davidiana and two others closely related deciduous species, Pourthiaea villosa and Pourthiaea arguta formerly included in the same genus Photinia, were observed. Differences were found in the colour of young leaves, the severity of cuticular folds on the adaxial side of the leaf, the presence/absence of lateral colleters, the shape of epidermal cells and their lateral walls, and the shape and number of stomata. These micromorphological differences are consistent with the phylogenetic position of Photinia-related species as determined by modern molecular data.