Plant Reproduction

Alternation of GenerationsAll plants have a diploid(2n) sporophyte generation that alternates with a haploid (1n) gametophyte generationIn bryophytes (mosses), the sporophyte is attached and dependent on the larger gametophyteIn vascular plants, the sporophyte is the larger generation.

Life Cycle of Flowering Plants

Flower: Function and nonessential parts

Function: to attract animals that carry pollen

Nonessential parts (not directly involved in reproduction)

Receptacle-the swollen tip of the branch

Sepals-leaflike structures that protect and surround a developing flower

Petals-brightly colored to attract animals

Essential Flower Parts:Female

Carpels often fuse to form one pistil.

The ovary is the base of the pistil.

The style is the stalk that arises from the pistil.

The stigma is the sticky tip of the style that captures pollen.

Essential Flower Parts:Male

The stamen is the male reproductive structure.

The anther is the tip of the stamen that produces pollen.

The filament is the stalk that supports the anther.

Gamete Formation:Pollen (male)

1. Through meiosis, pollen grains form in the anther.

2. In the pollen are the generative cell and tube cell.

3. The tube cell forms the pollen tube through which the generative cell travels.

4. The generative cell will form 2 sperm.

Gamete Formation:Ovule (female)

1. Ovules are compartments within the ovary.

2. Within each ovule, 8 nuclei form (1n).

3. 5 of the nuclei disintegrate.4. 1 of the nuclei becomes the egg.5. 2 nuclei are in the center and are

called polar nuclei.

Pollination: The transfer of pollen from anther to stigma (same species)

Cross pollination is when pollen goes to another plant structure (different genes).

Self-pollination is when the pollen stays on the same plant (less variety).

Fertilization: Gametes fuse.

1. After pollination, the tube cell forms a tube.

2. The generative cell becomes 2 sperm.

3. Both sperm enter the micropyle.

4. One sperm fertilizes the egg.

5. One sperm fertilizes the polar nuclei.

Results of Fertilization

An embryo (2n) surrounded by endosperm tissue (3n) that will nourish the embryo in the seed before germination.

This fertilization of egg and polar nuclei is known as double fertilization.

Dispersal of Fruits

and Seeds

Wind

Water

Animals

Seed GerminationCertain conditions are needed:

Water

Light

Temperature

Harsh

conditions