DEMO

EXTERNAL STRUCTURE OF FLOWERING PLANT

Objectives: By the end of this subtopic learners should be able to:
  1. Identify the parts of a flowering plant.
  2. State the functions of each part of a flowering plant.
  3. Differentiate insect pollinated from wind pollinated flowers.

Flowering plants

  • Sunflower
  • Maize
  • Beans
  • Tomato
These plants produce flowers, fruits and seeds.

Characteristics of Flowering Plants

  • Seeds grow in fruits, nuts or pods.
  • Sexual reproduction.
  • Vascular system in leaves, stems and roots.

Maize Plant Plants

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PLANT PART FUNCTIONS
Maize
Root
  • Holds the plant firmly.
  • Carry water and minerals from the soil up the plant
 
Stalk
  • Supports the plant, transports water and minerals throughout the plant
Leaf
  • Produce food for plant through the process of photosynthesis.
 
Tassel
  • Reproduction: produces pollen.
 
Silk
  • Reproduction: it captures pollen from the tassel.
 
Husk
  • Protects the maize seeds (fruit)
 
Fruit
  • Bears seeds
 
Seeds
  • Grows into a plant
 

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External parts of a bean flower and its functions

Plant Part Function
Bean
Stigma
  • Receives pollen grains from the anther.

 

Style
  • Hold the stigma and a tube which connect the stigma to the ovary.

 

Ovary
  • Produces ovules for fertilisation by anthers.

 

Ovule
  • Used to fuse pollen grains to produce a zygote.

 

Anthers
  • Produce pollen grains. (male part of the plant)

 

Petals
  • Attract pollinators

 

Sepals
  • Protect floral parts in the ovary.

 

Receptacle
  • Attaches the flower to the stem.

 


Pollination

  • It is the transfer of pollen grains from the anther to the stigma.
  • Pollen grains are immobile, they can not reach the stigma by themselves.
  • Pollen grains moved by external agents which include insects, water, gravity and growth contact.

Agents of pollination

  • Insects
  • Wind
  • Water

Self-pollination

  • Occurs when pollen grains from the anther of a flower to the stigma of either the same or genetically similar flower.
  • Self pollination maintains the parental characters or purity.

Cross pollination

  • Occurs when pollen grains lands on a different flower.

Comparisons between insect and wind pollinated flowers

Insect pollinated Wind pollinated
  • Produces nectar to attract insects
  • Have bright coloured petals to attract insect
  • Anthers are inside petals
  • Produce sticky pollen
  • No nectar
  • Small and dull coloured petals
  • Anthers are out of petals
  • Pollen is not sticky

Summary:

  • Pollination is the transfer of pollen grains from the anther to the stigma.
  • Maize is wind pollinated
  • Bean is insect pollinated
  • Wind, insects and water are agents of pollination.