Leaf morphological characteristics and taxonomic significance of ten species of Phoebe

Through an in-depth study of the leaf morphology of 10 species of Phoebe, to provide a theoretical basis for the identification and classification of Phoebe.

Through morphological observation combined with optical microscopy, scanning electron microscopy, and paraffin sectioning techniques, the taxonomic significance of leaf morphology, microscopic characteristics of leaf epidermis, and anatomical structure characteristics of leaves was deeply investigated.

1) The phenotypic traits of leaves exhibit significant differences. According to quantitative traits, they can be classified into four categories: extra-large leaves, large leaves, medium leaves, and small leaves. Within-species variation in leaf polymorphic traits with midrib above and below is stable. P. zhennan, P. bournei and P. hui present the morphological characteristics of the midrib being sunken on the upper surface and protruded on the lower surface. The backs of leaves, veins, and petioles of the 10 species all have hairs to varying degrees, with the most significant difference being the hairiness on the backs of leaves; 2) The anticlinal walls of the upper epidermis are straight to arched, and those of the lower epidermis are irregular and shallowly wavy. Stomata are only distributed on the lower epidermis. The stomatal morphology is similar among different species, but the stomatal density varies significantly, with the highest density in P. chekiangensis; 3) The cuticular ornamentation of the upper epidermis and the waxy ornamentation of the lower epidermis are diverse and differ among species. Epidermal hairs are distributed on the leaf epidermis of all species, all being unicellular hairs, and the density of epidermal hairs shows significant differences among different species; 4) The anatomical structure reveals that the leaves of the 10 Phoebe species are all bifacial leaves, composed of leaf epidermis, mesophyll tissue, and veins. The petioles are composed of epidermis, collenchyma, xylem, and phloem. There are significant differences in the palisade/spongy ratio, leaf thickness, and the distribution positions of mucilage cells among different species.

The leaf morphology and anatomical characteristics of the 10 Phoebe species are significantly different, which can provide important reference bases for the identification and classification of Phoebe.