What is the function of Gametophyte?
THE GAMETOPHYTE FUNCTION
• The spores, on germination give rise to the haploid gametophytes or prothalli that are usually small and insignificant structures. The gametophytes are inconspicuous as compared to the sporophytes. One of the most characteristic features of the pteridophytes is that the sporophyte has become the dominant morphological part of the life cycle while the gametophyte has been much reduced.For More Biology Doubts visit main page of Physics Wallah.
• The gametophytes are of two general types. Gametophytes that develop from homospores and grow upon the soil (outside the spore wall) to form independent plants, are known as exosporic gametophytes (e.g., Psilotum, Lycopodium sp. and Ophioglossum). Gametophytes, that develop from heterospores and most of the part retained within the original spore case, are called endosporic gametophytes (e.g., Selaginella, Isoetes and Marsilea).
• Exosporic gametophyte is typically a delicate, thin thallus and is commonly called the prothallus. In most of vascular cryptogams, the exosporic gametophytes grow exposed to light and remain attached to the ground by numerous rhizoids. In such cases they manufacture the food by means of their chloroplasts and live an independent life. The rhizoids are meant for the absorption and fixation.
• In some vascular cryptogams, the exosporic gametophytes are devoid of chlorophyll and are subterranean in habit. In such cases they obtain their food by symbiosis through the agency of mycorrhiza that occurs within the tissue of the prothallus or gametophyte, e.g., Psilotum, some species of Lycopodium and Ophioglossum.
• Endosporic gametophytes that develop from heterospores are greatly reduced structures. They develop largely or entirely within the spore wall and live on food deposited in the spores.