Search results
Results from the WOW.Com Content Network
However, not all heteromorphic gametophytes come from heterosporous plants. That is, some plants have distinct egg-producing and sperm-producing gametophytes, but these gametophytes develop from the same kind of spore inside the same sporangium; Sphaerocarpos is an example of such a plant. In seed plants, the microgametophyte is called pollen.
For example, plants produce gametes through mitosis in gametophytes. The gametophytes grow from haploid spores after sporic meiosis. The gametophytes grow from haploid spores after sporic meiosis. The existence of a multicellular, haploid phase in the life cycle between meiosis and gametogenesis is also referred to as alternation of generations .
The male gametophytes, which produce sperm, are enclosed within pollen grains produced in the anthers. The female gametophytes are contained within the ovules produced in the ovary . [ 2 ] [ 3 ] In some plants, multiple flowers occur singly on a pedicel (flower stalk), and some are arranged in a group ( inflorescence ) on a peduncle ...
At least one of the spores develop into haploid female gametophytes, the megagametophytes. [1] The megaspore mother cell arises within the megasporangium tissue. In flowering plants the megasporangium is also called the nucellus , and the female gametophyte is sometimes called the embryo sac or embryonic sac .
The sporophyte produces spores by meiosis, which in turn develop into gametophytes. Any sex organs that are produced by the plant will develop on the gametophyte. The seed plants, which include conifers and flowering plants, have small gametophytes that develop inside the pollen grains (male) and the ovule (female).
If the spores are deposited onto a suitable moist substrate they germinate to produce short, thin, free-living gametophytes called prothalli that are typically heart-shaped, small and green in color. The gametophytes produce both motile sperm in the antheridia and egg cells in separate archegonia. After rains or when dew deposits a film of ...
Seed plant gametophytes are extremely reduced in size; the archegonium consists only of a small number of cells, and the entire male gametophyte may be represented by only two cells. [27] Differentiation of the spores. All spores the same size (homospory or isospory). Horsetails (species of Equisetum) have spores which are all of the same size ...
These spores then germinate and divide by mitosis to form a haploid multicellular phase, the gametophyte, which produces gametes directly by mitosis. This type of life cycle, involving alternation between two multicellular phases, the sexual haploid gametophyte and asexual diploid sporophyte, is known as alternation of generations .