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Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. [1] It consists of pollen grains (highly reduced microgametophytes ), which produce male gametes (sperm cells).
The worker bees in the colony mix dry pollen with nectar and/or honey with their enzymes, and naturally occurring yeast from the air. Workers then compact the pollen. storing each variety in an individual wax hexagonal cell , typically located within their bee brood nest. This creates a fermented pollen mix call beekeepers call 'bee bread'. Dry ...
Flowers consist of a combination of vegetative organs – sepals that enclose and protect the developing flower. Petals attract pollinators, and reproductive organs that produce gametophytes, which in flowering plants produce gametes. The male gametophytes, which produce sperm, are enclosed within pollen grains produced in the anthers.
When bees go from flower to flower collecting pollen they are also depositing pollen grains onto the flowers, thus pollinating them. While pollen and nectar, in most cases, are the most notable reward attained from flowers, bees also visit flowers for other resources such as oil, fragrance, resin and even waxes. [52]
The pollen is carried to the pistil of another flower, by wind or animal pollinators, and deposited on the stigma. As the pollen grain germinates, the tube cell produces the pollen tube, which elongates and extends down the long style of the carpel and into the ovary, where its sperm cells are released in the megagametophyte.
Stigmas can vary from long and slender to globe-shaped to feathery. The stigma is the receptive tip of the carpel(s), which receives pollen at pollination and on which the pollen grain germinates. The stigma is adapted to catch and trap pollen, either by combining pollen of visiting insects or by various hairs, flaps, or sculpturings. [27]
These become pollen grains, within which the microspores divide twice by mitosis to produce a very simple gametophyte. Heterosporous plants that produced microspores in microsporangia and megaspores in separate megasporangia evolved independently in several plant groups during the Devonian period.
Pollen of angiosperms must be transported to the stigma, the receptive surface of the carpel, of a compatible flower, for successful pollination to occur. After arriving, the pollen grain (an immature microgametophyte) typically completes its development. It may grow a pollen tube and undergo mitosis to produce two sperm nuclei.