2.20 Floral structure of Apple

Question 1

Illustrated description of floral structure of Apple

Answer 1

Memorise diagram - Celia Davies page 113
Stigma (traps polen)
Filament (supports anther)
Sepal (protects flower when bud)
Nectary (produces nectar)
Petals (attract insects)
Ovule (egg)
Anther (makes pollen containing sperm)
Style stalk (pollen tube grows down)
Ovary (contains ovules)
Pollen Tube (carries sperm to ovules)

Question 2

Female parts of flower - Stigma, style, ovary

Answer 2

Stigma, style and ovary - collectively referred to as the PISTIL
All found in centre of flower:
5 x STIGMAs
5 x STYLEs (the stalks that hold the stigmas in place)
The OVARY (the wall which later becomes the apple core is divided into 5 parts, each part contains 2 OVULE
Each OVULE contains a female sex cell (gamete) as well as other structures - these later develop into seeds

Question 3

Male parts of flower - Stamens

Answer 3

Male part of the flower
Some form a circle around female structures (inner whorl)
Others surround the inner whorl (outer whorl)
Each stamen divided into two lobe anther carried by a ‘stalk’ called the FILAMENT
Pollen grans develop inside the anther lobes
Each pollen grain contains male sex cell (gamete = nucleus)
Pollen is used as a food reward for some insects

Question 4

Petals

Answer 4

Function = to attract insects
Large and colourful
Apple has 5 white or pinkish petals

Question 5

Sepals

Answer 5

Little green leaves surrounding and protecting the flower when in bud
The shrivelled structure on the fruit at the opposite end to the stalk

Question 6

Receptacle

Answer 6

The part of the stem from which the floral organs arise
Nectar is produced in its cells and collects on its surface (food for visiting insects)
Later swells to form the fleshy part of the apple that we eat

Question 7

Apple Fertilisation

Answer 7

Nectar easily washed out, diluted with dew due to open petal formation
Nectaries on the receptacle
Most are self sterile and require pollen from compatible tree
Stigma receptive on opening until DAY 3
5 days for pollen tube to grow then petals drop
Flower aborts after 7-8 days
Honeybee is only insect available in sufficient numbers to pollinate
In good weather bees will pollinate avidly but can be distracted by higher sugar content of dandellion