1. SEXUAL REPRODUCTION IN PLANTS
UNIT 4
The reproduction function
SEXUAL REPRODUCTION IN PLANTS
Natural Science 2. Secondary Education 1

2. Classifying plants are classified as which can be PLANTS
UNIT 4
Classifying plants
PLANTS
are classified as
SEEDLESS PLANTS
PLANTS WITH SEEDS
which can be
GYMNOSPERMS
ANGIOSPERMS
Click on each box to find out more
Natural Science 2. Secondary Education 2

3. Go back to the Start menu
UNIT 4
Classifying plants
Seedless plants
They do not have flowers, and they produce neither fruits nor seeds.
Reproduction occurs through the alternation of generations and they disperse via spores.
Two common examples are mosses and ferns.
Moss
Fern
Natural Science 2. Secondary Education
Go back to the Start menu 3

4. Go back to the Start menu
UNIT 4
Classifying plants
Gymnosperms
Their flowers are not particularly attractive and they almost always form structures called cones, often with separate genders.
Instead of producing fruit, the female cones mature into developed cones which contain seeds.
Some examples of gymnosperms are pine trees, firs and junipers.
Female cone
Seed
Male cone
Go back to the Start menu
Natural Science 2. Secondary Education 4

5. Go back to the Start menu
UNIT 4
Classifying plants
Angiosperms
Their flowers are generally attractive. They produce fruit, which contain seeds.
There are many different angiosperms, from small grasses to large trees.
Seed
Flower with androecium (stamen) and gynoecium (pistil)
Go back to the Start menu
Natural Science 2. Secondary Education 5

6. Parts of a typical flower
UNIT 4
Parts of a typical flower
Corrola
Petal
Stamen
Gynoecium or pistil
Androecium
Sepal
Click on androecium and gynoecium to find out more
Calyx
Natural Science 2. Secondary Education 6

7. Go back to the Start menu
UNIT 4
Parts of a typical flower
The androecium
It is made up of stamens. Each stamen has:
A filament to support the anther.
An anther, where pollen grains develop. Male gametes form inside these grains.
Anther
Pollen grains
Go back to the Start menu
Filament
Natural Science 2. Secondary Education 7

8. Go back to the Start menu
UNIT 4
Parts of a typical flower
The gynoecium
This is the female reproductive organ. It is shaped like a bottle.
It has three parts:
Ovary: the widest part, which contains the female gametes.
Style: the long part.
Stigma: the tip.
Stigma
Style
Ovary
Go back to the Start menu
Female gamete
Natural Science 2. Secondary Education 8

9. UNIT 4
Fertilisation 2
Pollen grain
When the pollen grain reaches the flower’s stigma it forms a pollen tube, which grows along the style until it reaches the ovary. 1
Pollination occurs.
Pollen tube 3
Female gamete
Male gametes travel down the pollen tube to the ovary and fertilisation takes place.
Male gametes
Natural Science. Secondary Education, Year 2 9

10. Seed and fruit formation
UNIT 4
Seed and fruit formation
The zygote and ovary develop into the seed and fruit
The walls of the ovary thicken. The zygote develops into a seed. 2 1
The flower withers and the corolla and the stamen fall away. The zygote begins to develop. 3
The fruit that envelops the seed is formed.
Natural Science 2. Secondary Education 10

11. Seed and fruit formation
UNIT 4
Seed and fruit formation
Parts of the seed
Endosperm: a nutritious substance that feeds the embryo
Cotyledons: small leaves that store nutrients.
Embryo
Hypocotyl
Radicle
Seedcoat: it envelops and protects the seed.
Natural Science 2. Secondary Education 11

12. Germination Germination 1 2 3
UNIT 4
Germination
Germination 1
The buried seed, in proper conditions, begins to absorb water. The embryo starts its development, using the nutrient supplies in the endosperm. 2
The seed coat breaks and a root and stem start to grow, the stem towards the surface and the root away from the surface. 3
When the stem breaks the surface, the cotyledons develop into leaves and begin to carry out photosynthesis. This is how the new plant will get nutrients, which will help it grow and develop.
Natural Science 2. Secondary Education 12