Summary
The pollinium of Epidendrum scutella, both in the anther and on the stigma, was examined with the electron microscope. The sporoderm of the outer tetrads has a sexine and an intine while that of the inner tetrads lacks a sexine, and an intine is formed only after the pollinium is on the stigma. A fibrous wall layer apparently holds the tetrads together. The cytoplasm is filled with plastids, mitochondria, polysomes, vacuoles and vesicles of various sizes, and endoplasmic reticulum (ER) with narrow cisternae. The vegetative nucleus is oval in form and contains a large nucleolus. The generative nucleus is deeply lobed and contains a well-developed nucleolus. The generative cytoplasm lacks both plastids and mitochondria and has little ER. Dictyosomes are present as well as assorted vesicles. A pocket is present between the plasma membrane of the generative cell and the wall; it contains assorted membranes and ribosome-like particles. After the pollen is on the stigma the wall surrounding the generative cell begins to disappear and gaps develop in it.
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This investigation was carried out during the tenure of a research fellowship from the Consejo Nacional de Investigaciones Científicas y Técnicas, Argentina.
Research supported by grants from National Science Foundation (GB-3460) and the Miller Institute for Basis Science at the University of California, Berkeley. The authors would like to thank Miss Mary Ashton for her assistance in the research.
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Cocucci, A., Jensen, W.A. Orchid embryology: Pollen tetrads of Epidendrum scutella in the anther and on the stigma. Planta 84, 215–229 (1969). https://doi.org/10.1007/BF00388107
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DOI: https://doi.org/10.1007/BF00388107