Stamen and Pollen Development

Abstract Stamens are the male sexual organs in flowers. Their function is to produce and disperse pollen, which carries the plant's sperm cells to the pistil. Mature stamens consist of a filament and an anther. They are initiated on floral meristems and form the third of four concentric organ whorls. The sterile filament provides a vascular connection and positions the anther for pollen dispersal. The anther sits at the tip of the filament and is the site of pollen production. Diploid germ‐line cells in the anther interior undergo meiosis to produce haploid microspores. These microspores, in turn, undergo one or two mitotic divisions, making pollen either bicellular or tricellular at the time of anthesis. Surrounding layers of nonsexual cells are essential for pollen development and also contribute to the external pollen coat. At anthesis, the mature anther splits open, and pollen is available for transfer to the pistil. Key Concepts A canonical flower contains four concentric organ whorls. Stamens comprise the third whorl and function to produce and disperse pollen, which contains the male gametes. Stamens are specified by the combined action of B‐ and C‐class floral homeotic genes in a floral meristem. A mature stamen consists of a nonsexual filament and a four‐lobed anther that is the site of pollen production. Positional information and cell–cell signalling are crucial for specifying the germ‐line pollen mother cells and surrounding somatic tissues. Cells in the interior of the developing anther differentiate into germ‐line archesporial cells and then induce somatic fates in surrounding cells. After meiosis, the germ‐line archesporial cells develop into pollen, and the surrounding somatic cells support pollen development. At anthesis, the mature anther splits and desiccates to allow pollen dispersal.