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Diagram showing the alternation of generations between a diploid sporophyte (bottom) and a haploid gametophyte (top) A sporophyte (/ ˈ s p ɔːr. ə ˌ f aɪ t /) is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
In liverworts, mosses and hornworts, the dominant form is the haploid gametophyte. The diploid sporophyte is not capable of an independent existence, gaining most of its nutrition from the parent gametophyte, and having no chlorophyll when mature. [21] Sporophyte of Lomaria discolor, a fern ; Dominant sporophyte (sporophytic).
Heterospory stops self-fertilization from occurring in a gametophyte, but does not stop two gametophytes that originated from the same sporophyte from mating. [8] This specific type of self-fertilization is termed as sporophytic selfing, and in extant plants it occurs most commonly among angiosperms .
In biology, a spore is a unit of sexual (in fungi) or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. [1] Spores form part of the life cycles of many plants , algae , fungi and protozoa . [ 2 ]
[3] [4] The pyrenoid is a liquid-like organelle which enables a more efficient photosynthesis, [5] has evolved independently five to six times in hornworts and is present in half of the roughly 200 species. [6] It is formed by the fusion of the chloroplast with other organelles and is composed predominantly of RuBisCO, the key enzyme in carbon ...
The mature sporophyte produces spores by meiosis, sometimes referred to as reduction division because the chromosome pairs are separated once again to form single sets. In mosses and liverworts, the gametophyte is relatively large, and the sporophyte is a much smaller structure that is never separated from the gametophyte.
Pollen itself is not the male gamete. [4] It is a gametophyte, something that could be considered an entire organism, which then produces the male gamete.Each pollen grain contains vegetative (non-reproductive) cells (only a single cell in most flowering plants but several in other seed plants) and a generative (reproductive) cell.
The gametophyte (haploid) structures are shown in green, the sporophyte (diploid) in brown. Like all land plants (embryophytes), bryophytes have life cycles with alternation of generations . [ 11 ] In each cycle, a haploid gametophyte, each of whose cells contains a fixed number of unpaired chromosomes , alternates with a diploid sporophyte ...