Plant Reproduction

Flower Anatomical Terms The male Stamen is composed of a Filament and Anther The female Carpel (or Pistil) is composed of the Stigma, Style, and Ovary (where the ovule forms) Accessory reproductive structures include the sepals and petals.

Pollen Grain Formation Inside the anther four masses of spore- producing cells (2n) are formed through mitosis producing pollen sacs Individual cells now forms 4 Microspores (n) through meiosis. Each microspore forms two sperm cells (n) contained within a single pollen grain

Egg Formation Inside the ovule an individual spore- producing cell (2n) forms 4 Megaspores (n) through meiosis. Three of the megaspores disintegrate while the remaining megaspore completes 3 mitotic division without cytokinesis. Later unequal cytoplasmic division produces 7 cells, six that are haploid (1n) (one is the egg) and one that is (n+n) called the endosperm mother cell

Double Fertilization When a pollen grain land on a receptive stigma (Pollination) the two sperm cells contained within burrow through the pollen grain. One sperm cell forms the Pollen Tube from the stigma, through the style, and to the ovule where it fertilizes the 2n megaspore forming Endosperm (seed & plant food) The other sperm cell fertilizes the egg cell forming the zygote of the seed.