Gametophyte
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The gametophyte (Greek gamete, gametes “wife, husband” and phyton “plant”) is the gamete- forming, sexual generation in plants, i.e. the haploid phase of the generation change . The diploid phase is called the sporophyte . This creates spores in lower plants ( mosses and ferns ) , which are used for asexual reproduction .
A gametophyte is always multicellular. It grows from a meiospore of a sporophyte and is therefore always haploid , so each of its cells has only one set of chromosomes . The gametophyte develops sexual organs (called antheridia and archegonia ) and in these the gametes. The fusion of two sex cells results in a diploid zygote , which is at the beginning of the second generation (the diploid sporophyte generation ). In other words: after nuclear fusion, the zygote grows into a sporophyte; this creates spores from which a gametophyte emerges and thus closes the cycle of the two generations.
The gametophytes of the mosses are the green moss plants. In ferns, the gametophytes (called: prothallium ) are so greatly reduced that they are hardly ever noticed and can easily be mistaken for liverwort ; the well-known "fern plant" is the sporophyte.
The gametophytes of the seed plants are even further reduced . In them, the male gametophyte is in the pollen grain and consists in the angiosperms (flowering plants) of only three cells. The female gametophyte is the embryo sac in the ovule ; fully developed, it usually consists of seven cells.
literature
- Textbook of Plant Sciences, 37th edition, Springer, Berlin / Heidelberg 2014, p. 572.