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The taxonomy of Paphiopedilum Pfitz. has been disputed and needs more data for clarification. Floral morphology and anther development in P. purpuratum were observed using microscope and paraffin section. The results were as follows: (1) It was supported that P. purpuratum should be placed in Paphiopedilum subgenus Paphiopedilum sect. Barbata by some floral features, including a single flower, sepal white with veins, petal spotted with blackish-maroon, pouch of a lip auriculate on both sides, and a staminode lunate. (2) At the early stage, anther primordium developed into a pair of laterally juxtaposed thecae. An incomplete sterile septa was differentiated in the center of each theca, giving rise to two arc-shaped microsporangia. When anther split, the sterile septum was discomposed and degenerated resulting in a mass of sticky pollens from two pollen sacs were fused into a unit. (3) The developed anther wall consisted of an epidermis, an endothecium, a middle layer, and a tapetum, conforming to the monocotyledonous type. Both tapetum and the inner tapetum cells contained 2 nuclei. At the stage of 2-celled grains, degeneration occurred in the epidermis and tapetum layers, while the endothecium became thickened fibrously. (4) Microspore mother cells underwent a simultaneous cytokinesis resulting in microspore tetrads with varied arrangements of tetrahedral, isobilateral, and decussate types, and the meiotic activity of microspore mother cells in the same theca was obviously asynchronous and different meiosis phases could be observed. (5) Microspores produced 2-celled pollens via a mitosis, which could be retained in pollen tetrads or released as monad. Based on the data available, some key features are selected for taxonomy and conservation biology of Paphiopedilum in Cypripedioideae, including the differentiation of incomplete sterile septum, the monocotyledonous type of anther wall, the binucleated tapetum, differentiation of the inner tapetum, simultaneous cytokinesis, the sticky pollens, and so on. This study provides new information for taxonomy and conservation biology of Paphiopedilum, as well as of Cypripedioideae.

The taxonomy of Paphiopedilum Pfitz. has been disputed and needs more data for clarification. Floral morphology and anther development in P. purpuratum were observed using microscope and paraffin section. The results were as follows:(1)It was supported that P. purpuratum should be placed in Paphiopedilum subgenus Paphiopedilum sect. Barbata by some floral features, including a single flower, sepal white with veins, petal spotted with blackish-maroon, pouch of a lip auriculate on both sides, and a staminode lunate.(2)At the early stage, anther primordium developed into a pair of laterally juxtaposed thecae. An incomplete sterile septa was differentiated in the center of each theca, giving rise to two arc-shaped microsporangia. When anther split, the sterile septum was discomposed and degenerated resulting in a mass of sticky pollens from two pollen sacs were fused into a unit.(3)The developed anther wall consisted of an epidermis, an endothecium, a middle layer, and a tapetum, conforming to the monocotyledonous type. Both tapetum and the inner tapetum cells contained 2 nuclei. At the stage of 2-celled grains, degeneration occurred in the epidermis and tapetum layers, while the endothecium became thickened fibrously.(4)Microspore mother cells underwent a simultaneous cytokinesis resulting in microspore tetrads with varied arrangements of tetrahedral, isobilateral, and decussate types, and the meiotic activity of microspore mother cells in the same theca was obviously asynchronous and different meiosis phases could be observed.(5)Microspores produced 2-celled pollens via a mitosis, which could be retained in pollen tetrads or released as monad. Based on the data available, some key features are selected for taxonomy and conservation biology of Paphiopedilum in Cypripedioideae, including the differentiation of incomplete sterile septum, the monocotyledonous type of anther wall, the binucleated tapetum, differentiation of the inner tapetum, simultaneous cytokinesis, the sticky pollens, and so on. This study provides new information for taxonomy and conservation biology of Paphiopedilum, as well as of Cypripedioideae. [ABSTRACT FROM AUTHOR]

Although most of angiosperms have bisexual flowers, unisexuality has evolved in different angiosperms lineages. Bisexual flowers have been reported for the majority of species in Cactaceae; however, three of four subfamilies have members with unisexual flowers. Mammillaria dioica (Cactoideae) has been reported having unisexual flowers in gynodioecious, dioecious or trioecious breeding systems. However, a developmental study is missing to clarify the breeding system and the anther or ovule abortion process. This study describes breeding system and embryology of M. dioica from a population at Baja California Sur, México, through the careful examination of floral morphology and by using light and scanning electron microscopy at different stages of floral development. Hermaphrodite and female individuals were identified in the population with a ratio of 67.5% and 32.5% respectively. In pistillate and bisexual flowers, the ovary presents many campylotropous, bitegmic and crassinucellate ovules with well-formed style and stigma, likewise both morphs produce fruits and seeds. Moreover, in bisexual flowers, stamens are well-developed and contain pollen grains, anther wall development is of the monocotyledonous type, the microspore tetrads are tetrahedral, and mature pollen grain is three-celled with reticulate exine and tricolpate. In pistillate flowers, the anthers develop just before the meiosis of the microspore mother cells, and are collapsed at anthesis; the tapetum is bi-layered and exhibits abnormal growth, each cell is uninucleate in both layers. The inner layer of tapetum develops fibrous reticulate cell wall thickenings, while endothecium develops U-shapes cell wall thickenings. No tapetal secretory layer was observed, which means a fail to support the development of microspore mother cells. This male sterility phenotype has not been reported for other species of Cactaceae with unisexual flowers neither flowering plants. [ABSTRACT FROM AUTHOR]

This study aimed to elucidate the anther wall development, pollen wall development, and exine structure of Trochodendron aralioides Siebold and Zuccarini, a tree with primitive vessels but long considered to lack vessel elements in its wood. The anther wall is the basic type: epidermis, endothecium layer, three middle layers, and tapetum. The anther tapetum is glandular and cells are uniseriate. Microspore mother cells undergo meiosis with simultaneous cytokinesis to produce tetrahedral tetrads enclosed within a callose wall. Before development of the protectum, primexine is inserted against the callose, and the plasma membrane is invaginated. Then, the probacula are elongated under the protectum and arise basally from the plasma membrane. The foot layer formation is concomitant with callose wall dissolution. The foot layer is thick, and the endexine is thin. The foot layer and the endexine are both continuous. The intine is initially formed in the vacuolated microspore stage. Hollow Ubisch bodies are observed on the inner surface of the tapetum in free microspore stage. Pollen grains are tricolporate and 2-celled at the time of shedding. The numerous anthers of a single flower are at different development stages in both protandrous and protogynous individuals. [ABSTRACT FROM AUTHOR]

Abstract: Anther wall development, microsporogenesis and microgametogenesis were compared between a normal male fertile chrysanthemum cultivar ‘NJAU04-29-2’ and the two male sterile selections ‘rm20-11’ (anther indehiscent) and ‘NJAU05-52-2’ (anther aborted). In both of the two male sterile types, the tapetum enlarged abnormally and showed signs of disorganization of walls at the onset of meiosis, the pollen was aborted, the anthers appeared shrunken, and the anther vascular bundle and connective tissue were degenerated by anthesis. In ‘rm20-11’, the two smaller pollen sacs began to degenerate at the microsporogenesis stage, so that only one or two microsporangia developed, while in ‘NJAU05-52-2’, only one or two microsporangia were formed following the archesporial cell stage, and most of the microspore mother cells degenerated during the course of meiosis. [ABSTRACT FROM AUTHOR]

Critical morphological synapomorphies have not been found in support of the Acoranan hypothesis, the molecular phylogenetic discovery that Acoranae are the basal monocots. The previously undetermined pattern of anther wall development in Acorus has been suggested to be one such character. Two main types of anther wall development have been recognized: 1) the “monocotyledonous” type, which characterizes both monocots and dicots, and 2) the “dicotyledonous” type, which is almost exclusively found among dicots. An anatomical study of anther wall development in Acorus was here undertaken using the electron microscope. Development of the anther wall in Acorus was found to be somewhat irregular or perhaps even intermediate between the two types although largely consistent with the “monocotyledonous” type. The presumed significance of anther wall development and other critical morphological characters to the Acoranan hypothesis in the absence of knowledge about the sister group to the monocots is evaluated. [ABSTRACT FROM AUTHOR]