Unit 9: Plants                                                                1   2   3   4   5   6

3.2. The reproductive organs of Spermatophytes

a) The flower

Flowers are the reproductive organs of Spermatophytes.

They are formed by several groups of modified leaves join together

in the receptacle.

- Stamens (male reproductive part)

     Every one is formed by a filament and an anther.

     Anther contains the pollen grains (male gametes).

- Pistil (female reproductive part)

     It is formed by a group of fused leaves (carpels).

     It is divided into: stigma, style and ovary.

      Inside the ovary are the ovules (female gametes).

- Petals

     They are coloured leaves which function is to attract insects.

     Collectively they are called corolla.

- Sepals

     They are green leaves located below the petals which protect the flower.

     Collectively they are called calyx.

A flower that contains all these elements is a complete flower.

But some flowers do not have some elements (corolla or calyx).

They are incomplete flowers.

Flower can be unisexual (they only have stamens or carpels) or

hermaphrodites.

Usually flowers are in groups called inflorescences.

b) The seed and the fruit

Angiosperms produce fruit: structures that come from the flower's ovary and that contain one or several seeds. The ovule of the flower changes into the seed and the walls of the ovary change into the fruit.

3.4. Label this diagram. What does it represent?

        Then listen the descriptions and relate each one with the described part.