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

• Main Author: Ravi Kant
• Format: Article
• Language: English
• Published: National Taiwan University 2019-07-01
• Series: Taiwania
• Subjects: Anther wall; Binucleate tapetum; Calanthe tricarinata; Caudicle; Orchid; Pollinium; Septum
• Online Access: http://tai2.ntu.edu.tw/taiwania/abstract.php?type=abstract&id=1624

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.