Observation of the morphological and anatomical characteristics of male flower bud development in Litsea cubeba(Lour.) Pers.

To clarify the process of flower bud development in male flowers of Litsea cubeba(Lour.) Pers., we investigated the differentiation and development of the morphology and anatomy of male flower buds using stereomicroscopy, paraffin technology, and scanning electron microscopy. The results showed that: (1) The differentiation period of the male flower bud in L. cubeba was divided into five stages, including undifferentiation, inflorescence primordium differentiation, bract primordium differentiation, flower primordium differentiation, and floral organ differentiation, with the last stage further subdivided into perianth primordium differentiation, stamen primordium differentiation, and pistil primordium differentiation. There was some overlap in each differentiation stage. Flowering was from early January to late March the following year. (2) Mature L. cubeba males had unique irregular green stamen nectaries, which were borne at the base of the inner stamens, distributed on both sides of the filaments, intertwined with the filaments of the inner and outer stamens, and closely connected with the inner filaments. (3) Each anther had four pollen sacs and the development of the anther wall followed the basic model. The tapetum was glandular. Microspores were continuous during meiosis cytokinesis, and mature pollen grains were 2-pollen cells with very few microspore abortion during development. There were more spikes in ripe pollen exine, which was base dilated, and the exposed portion of the outer wall showed a rough, non-thin wall area, with a few small perforations. (4) Most pistils were arrested when the suture of abdominal cells formed into a peritoneal cavity. Therefore, the pistil had no stigma, and the style was shortened or missing,which process was called degradation. Fertilization did not happen until the end of flowering. The process was called degradation. We directly obtained the characteristics and patterns of male flower bud development, as well as the corresponding external morphogenesis, microsporogenesis, male gametophyte development, shedding, and development process of the pistillode in L. cubeba. These results provide a reference for the florescence regulation,selection and breeding of superior varieties of L. cubeba.