Plants Sexual reproduction

1 plants

1.1 flowering plants
1.2 ferns
1.3 bryophytes

plants

animals typically produce gametes directly meiosis. male gametes called sperm, , female gametes called eggs or ova. in animals, fertilization follows after meiosis. plants on other hand have mitosis occurring in spores, produced meiosis. spores germinate gametophyte phase. gametophytes of different groups of plants vary in size; angiosperms have few 3 cells in pollen, , mosses , other called primitive plants may have several million cells. plants have alternation of generations sporophyte phase succeeded gametophyte phase. sporophyte phase produces spores within sporangium meiosis.

flowering plants

flowers sexual organs of flowering plants.

flowering plants dominant plant form on land , reproduce either sexually or asexually. distinguishing feature reproductive organs, commonly called flowers. anther produces pollen grains contain male gametophytes (sperm). pollination occur, pollen grains must attach stigma of female reproductive structure (carpel), female gametophytes (ovules) located inside ovary. after pollen tube grows through carpel s style, sex cell nuclei pollen grain migrate ovule fertilize egg cell , endosperm nuclei within female gametophyte in process termed double fertilization. resulting zygote develops embryo, while triploid endosperm (one sperm cell plus 2 female cells) , female tissues of ovule give rise surrounding tissues in developing seed. ovary, produced female gametophyte(s), grows fruit, surrounds seed(s). plants may either self-pollinate or cross-pollinate.

nonflowering plants ferns, moss , liverworts use other means of sexual reproduction.

in 2013, flowers dating cretaceous (100 million years before present) found encased in amber, oldest evidence of sexual reproduction in flowering plant. microscopic images showed tubes growing out of pollen , penetrating flower s stigma. pollen sticky, suggesting carried insects.

ferns

ferns produce large diploid sporophytes rhizomes, roots , leaves; , on fertile leaves called sporangium, spores produced. spores released , germinate produce short, thin gametophytes typically heart shaped, small , green in color. gametophytes or thallus, produce both motile sperm in antheridia , egg cells in separate archegonia. after rains or when dew deposits film of water, motile sperm splashed away antheridia, produced on top side of thallus, , swim in film of water archegonia fertilize egg. promote out crossing or cross fertilization sperm released before eggs receptive of sperm, making more sperm fertilize eggs of different thallus. zygote formed after fertilization, grows new sporophytic plant. condition of having separate sporephyte , gametophyte plants called alternation of generations. other plants similar reproductive means include psilotum, lycopodium, selaginella , equisetum.

bryophytes

the bryophytes, include liverworts, hornworts , mosses, reproduce both sexually , vegetatively. small plants found growing in moist locations , ferns, have motile sperm flagella , need water facilitate sexual reproduction. these plants start haploid spore grows dominate form, multicellular haploid body leaf-like structures photosynthesize. haploid gametes produced in antherida , archegonia mitosis. sperm released antherida respond chemicals released ripe archegonia , swim them in film of water , fertilize egg cells producing zygote. zygote divides mitotic division , grows sporophyte diploid. multicellular diploid sporophyte produces structures called spore capsules, connected seta archegonia. spore capsules produce spores meiosis, when ripe capsules burst open , spores released. bryophytes show considerable variation in breeding structures , above basic outline. in species each plant 1 sex while other species produce both sexes on same plant.