Development of Monads and Associated Changes in Anther in Cypripedium cordigerum D. Don. : A rare Orchid
Development of monads and corresponding changes in anther has been studied in Cypripedium cordigerum D. Don. (subfamily Cypripedioideae), a rare orchid of temperate Himalaya. Anthers are tetrasporangiate. Each anther has two thecae oriented towards the labellum. In each theca, a septum is formed. At the pollen mother cell stage, anther wall is 6-7 layered. Pollen mother cells undergo simultaneous type of cytokinesis and result into rhomboidal, isobilateral, tetrahedral, decussate, T-shaped and linear types of microspore tetrads in different concentrations. Nucleus of a microspore remains in the centre and divides to form a generative cell and a vegetative cell. Along with endothecium, connective as well as sterile septum also develops fibrous thickenings. Pollen grains dispersed as monads or single grains. Scanning Electron Microscope (SEM) studies of pollen grains have shown that exine surface is tectate with one-two elongate furrows. A deviation has been observed from other orchids during the development of monads in the present taxon. On the basis of this deviated behavior, the present taxon can be easily differentiated from other members of the family, Orchidaceae.