Development of pollinium and associated changes in anther of Calanthe tricarinata Lindl., an epidendroid orchid

Development of pollinium and associated changes in anther of Calanthe tricarinata Lindl., an epidendroid orchid

In Calanthe tricarinata Lindl., anther primordium develops two thecae each with a mass of densely cytoplasmic archesporial cells surrounded by the protoderm. A six-layered anther wall develops from the archesporial cells of hypodermal layer. Cells in the tapetum are binucleate, only reported in a few primitive orchids. Formation of two septa in each theca results into eight microsporangia which is a primitive character. Pollen mother cells undergo simultaneous cytokinesis and form tetrahedral, rhomboidal, decussate, T-shaped, square and linear type of microspore tetrads. Pollen grains unite to form eight pollinia, which is a primitive feature in the family Orchidaceae. Pollinia unite to the viscidium through long caudicles to form a structure called the pollinarium unit. Pollen grains are monoaperturate with smooth exine. Present observations contribute significantly in the taxonomy and understanding character evolution in the family Orchidaceae.