Search

Species of sect. Chrysantha have high ornamental value, but their classifications are controversial. In order to study the morphological characteristics and taxonomic significance of pollen in sect. Chrysantha, we observed morphological shape, exine ornamentations and perforation characteristics of 10 species of sect. Chrysantha pollen grains by scanning electron microscope, and the polar axis, equatorial axis and length of germination groove were analyzed by clustered. The results were as follows:(1)The pollen of sect. Chrysantha was medium-sized and most of them were subspherical, only C. indochinensis var. tunghinensis was oblate sphere and C. impressinervis was prolate; The extine ornamentation of pollen could be broadly divided into three types: tuberculate-baculate, ornate and verrucate, and the size and density of surface perforation were obviously different.(2)Cluster analysis showed that the pollen morphology of C. perpetua, C. petelotii var. grandiflora, C. petelotii and C. euphlebia were proximity; C. flavida, C. indochinensis, C. micrantha and C. indochinensis var. tunghinensis had similar characteristics; However, C. pubipetala and C. impressinervis were clearly different from the others. The extine ornamentation and perforation of pollen were different, but it was still necessary to combine the polar axis, equatorial axis and the length of germination groove to clearly distinguish the 10 species of sect. Chrysantha. From the perspective of palynology, the pollen of sect. Chrysantha has the general characteristics of Camellia without specificity, and this group plants may not be an independent group, but the pollen morphology of this group plants has obvious inter-specific differences, which can be used as the basis for taxonomy. The results of this study provide the basis for the taxonomic status among species of sect. Chrysantha. [ABSTRACT FROM AUTHOR]

In order to study the morphological diversity of Hibiscus syriacus cultivars and their relationships, we observed morphological characteristics and exine sculpture of 22 H. syriacus pollen grains by scanning electron microscope, and used R-type cluster analysis and principal component analysis to extract appropriate indicators for UPGMA cluster analysis. The results were as follows:(1)The pollen of H. syriacus was single-spherical, nearly spherical with diameter of 148.98-111.65 μm with thorn-like ornamentation on the surface with length of 27.42-14.79 μm; The tip of the thorn was sharp, and the thorns distributed around scattered pores; The pollen surface was distributed with granular protrusions and the apertures were irregular.(2)UPGMA cluster analysis was performed after extracting principal components of the measured indicators. When the Euclidean mean distance threshold was 6, 22 H. syriacus cultivars were divided into six categories. The single-petal blue-violet cultivars 'Bluebird', 'Dan Ban Zi Fen' and 'Xi Ye' had close relationships, and semidouble cultivars 'Lavender Chiffon' and 'China Chiffon', 'Pink Chiffon' had close relationships, while white single-petal 'Wood Bridge' and 'Hamabo' were relatively close. It was believed that the single-petal blue-violet cultivars in H. syriacus were more primitive than the pink and white semidouble cultivars, while purple semidouble cultivars were more evolved and the white single-petal cultivars were highly evolved. The results of this study provide theoretical basis for genetic evolution, taxonomic status, and genetic relationship studies in H. syriacus. [ABSTRACT FROM AUTHOR]