Development of anther and sectile pollinium in Herminium lanceum (Thunb. ex Sw.) Vuijk-a massulate orchid

Abstract

The role of anther characteristics in orchid taxonomy, cladistic analysis, and understanding the development and evolution of various traits is significant. Therefore, Herminium lanceum (Thunb. ex Sw.) Vuijk was selected for the study due to the lack of information about these characteristics. In this taxon, anther primordium developed two thecae directed towards the lateral side, which produced wedge-shaped, rectangular or triangular massulae through repeated mitotic divisions of archesporial cells. The anther wall developed from the outer secondary parietal layer and inner secondary parietal layer, made up of epidermis, endothecium, a middle layer, and tapetum. Each theca had a central septum that divided it into two microsporangia. Tapetum of dual origin was observed. Cytokinesis produced isobilateral, tetrahedral, linear, T-shaped and decussate types of microspore tetrads. Each microspore had a smaller lenticular generative cell and a larger spherical vegetative cell, which were formed by the mitotic division of the nucleus. Additionally, the endothecium developed ring-shaped fibrous thickenings. Massulae of two locules were united to the reticulum and formed bipartite sectile pollinium.