Life Cycles:

Phylum Pinophyta:

  • Pinophyta are gymnosperms.

    • Gymnosperms are seedless, vascular plants

  • In pinophyta, the sporophyte generation is dominant.

    • Both male and female reproductive structures are found on the sporophyte

    • The sporophyte is diploid (2n)

  • Sporophyte makes microspores via meiosis (n) which form the pollen grain— male gametophyte, (n), through mitosis.

  • The sporophyte also produces ovule cones which develop ovules via meiosis which contain megasporangia.

  • The pollen fertilizes one of the eggs contained in the ovule cone, forming a diploid zygote.

    • Pollen uses pollen tube to fertilize egg.

    • NO DOUBLE FERTILIZATION: there is only one sperm that fertilizes one egg.

      • No fruit (ovary) is formed

  • The sporophyte drops the ovule cones and the embryo-containing seeds are able to disperse (via amenochory) and grow into the next generation of (2n) sporophytes.

Phylum Anthrophyta:

  • The mature anthrophyta sporophyte is the dominant generation. It is also diploid (2n).

    • Anthrophyta are covered-seed vascular plants.

  • The anthrophyta sporophyte’s male reproductive structure goes through meiosis and forms a haploid microspore, which then goes through mitosis, forming two nuclei.

  • The female reproductive structure goes through meiosis to form an/a ovule(s) and then goes through mitosis. There are three eggs (n).

  • The pollen forms a pollen tube and one fertilizes the first egg while the remaining nucleus fertilizes the two polar bodies.

    • This is called double fertilization and leads to the production of an ovary which makes fruit.

    • Second sperm forms endosperm (3n) which forms the nutritive tissue in the seed.

  • Mitosis happens, and the embryo develops inside the ovule which is inside the developing ovary.

  • The seed is dispersed and forms a growing (2n) sporophyte.

Phylum Bryophyta:

  • The Sporophyte (2n) grows out of a mature female gametophyte (n).

  • Spores (n) are produced via meiosis, and are released into the AIR

    • SPORES = AIR

    • The spores go through mitosis after meiosis when turning into gametophytes from their spore stage

  • The gametophytes (n) mature

    • The male gametophyte releases sperm from the antheridia which use WATER

      • SPERM = WATER

    • The sperm make it to the mature female sporophyte’s archegonia which contains the egg, and fertilize the zygote.

The zygote goes through mitosis to turn into a mature sporophyte (2n) on top (dependent) on the mature female gametophyte (n).

Phylum Pteridophyta:

  • The mature sporophyte (2n) goes through meiosis and releases spores from the sori.

  • The spores land, and go through mitosis to produce gametophytes (n).

    • There is an archegonium and an antheridium on the gametophyte, with each one maturing at a different rate so as to prevent self-fertilization

  • The sperm swim from the antheridium to the archegonium and fertilize the egg making a zygote.

  • The sporophyte grows from the fertilized archegonium off of the gametophyte.