Pollengrain sentence example

pollengrain
  • The mature pollengrain is, like other spores, a single cell; except in the case of some submerged aquatic plants, it has a double wall, a thin delicate wall of unaltered cellulose, the endospore or intine, and a tough outer cuticularized exospore or extine.
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  • After the entrance of the pollengrain the pollen-chamber becomes roofed over by a blunt protuberance of nucellar tissue.
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  • There are also rounded portions of the membrane or pores visible in the pollengrain; these vary in number from one to fifty, and through one FIG.
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  • Lower part of canal, enlarged; o, cavity of canal, surrounded by a sheath of cells, dilated towards the bottom of canal, in which a large pollen-grain is caught; ex, exterior of pollengrain; in, internal group of prothallial or antheridial cells.
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  • Before leaving the pollen-sac a division takes place in the pollengrain into a vegetative cell or cells, from which the tube is developed, and a generative cell, which ultimately divides to form the male cells (see Angiosperms and Gymnosperms).
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