Life cycle of an angiosperm (flowering plant).

A plant alternates between a multicellular diploid (2n) sporophyte and a multicellular haploid (n) gametophyte generation.

  1. A mature plant is a multicellular diploid sporophyte with reproductive structures.

  2. Anthers contain microsporangia in which germ cells divide by meiosis to produce microspores.

  3. Ovaries contain megasporangia in which germ cells divide by meiosis to yield 4 megaspores each.

  4. Microspores divide by mitosis to form multicellular male gametophytes (pollen grains), which contain sperm cells.

  5. One of the 4 megaspores divides by mitosis to form a multicellular female gametophyte (embryo sac), which contains an egg cell in an ovule.

  6. Fertilization (pollination) occurs when a sperm fuses with an egg, producing a diploid single-celled zygote.

  7. The zygote develops by mitosis to produce the sporophyte.