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Gametophytes produce haploid sperm and eggs which fuse to form diploid zygotes that grow into sporophytes. Sporophytes produce haploid spores by meiosis , that grow into gametophytes. Bryophytes are gametophyte dominant, [ 11 ] meaning that the more prominent, longer-lived plant is the haploid gametophyte.
In bryophytes (mosses, liverworts, and hornworts), the gametophyte is the most visible stage of the life cycle. The bryophyte gametophyte is longer lived, nutritionally independent, and the sporophytes are attached to the gametophytes and dependent on them. [5] When a moss spore germinates it grows to produce a filament of cells (called the ...
Seed plant gametophytes are also dioicous. However, the parent sporophyte may be monoecious, producing both male and female gametophytes or dioecious, producing gametophytes of one gender only. 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 ...
Most bryophytes, such as these mosses, produce stalked sporophytes from which their spores are released. The non-vascular land plants, namely the mosses (Bryophyta), hornworts (Anthocerotophyta), and liverworts (Marchantiophyta), are relatively small plants, often confined to environments that are humid or at least seasonally moist.
A cluster of antheridia is called an androecium while a cluster of archegonia is called a gynoecium. (Note these terms have a different meaning when used to refer to flower structures.) Bryophytes have the most elaborate gametophytes of all living land plants, and thus have a wide variety of gametangium positions and developmental patterns.
In ferns and seed plants (including cycads, conifers, flowering plants, etc.) the sporophyte is the dominant generation; the obvious visible plant, whether a small herb or a large tree, is the sporophyte, and the gametophyte is very small. In bryophytes and ferns, the gametophytes are independent, free-living plants, while in seed plants, each ...
In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains and in most of these the antheridia have been reduced to a single generative cell within the pollen grain. During pollination, this generative cell divides and gives rise to sperm cells.
In flowering plants, the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac. The sporophyte produces spores (hence the name) by meiosis, a process also known as "reduction division" that reduces the number of chromosomes in each spore mother cell by half. The resulting meiospores develop into ...