Teacher Resource 2 – Dissection of a flower
Introduction
In this practical, you will firstly examine and identify the main structures of a lily flower.
You will then carefully cut the flower in half and make a cross-sectional drawing.
You will study pollen from the flower under the microscope and measure the diameter of a pollen
grain.
The structure of a flower from grass will then be examined.
Finally you will look at grass pollen using a microscope and calculate the diameter of a pollen
grain.
Equipment
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Microscope
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Microscope slides
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Coverslips
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Lilly flower
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Grass in flower
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Scalpel or single edged razor blade
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White tile
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Forceps
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Dropping pipettes
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Tap water
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Eyepiece graticule
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Stage micrometer
Health and safety
Make a list of any health and safety issues involved with the procedure.
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The effects of ageing on the reproductive system
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Instructions
1. Firstly examine your lily flower and identify the following structures:- petal, sepal, stigma, style,
anther and filament.
2. Then cut you flower using a scalpel, in line with the stem, to produce a half flower. Identify the
ovary. Use a hand lens to look at the structures you have identified in more detail.
3. Make an annotated drawing of the half flower.
4. Using a paintbrush, remove some pollen grains from the anther of the flower. Place on a
microscope slide, add a drop of water and carefully cover with a coverslip.
5. Use a stage micrometer to calibrate the eyepiece graticule for use with x4 and x10 objective
lenses. Make a note of each calibration for later use.
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Plant reproduction
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6. Examine the pollen under the microscope. Use the eyepiece graticule to calculate the diameter
of a pollen grain.
7. Now examine a flower from your grass. Use a hand lens to try to identify the flower parts.
Make a drawing of the flower.
8. Using a clean paintbrush, remove pollen from the grass, mount it on a microscope slide and
using the eyepiece graticule, calculate the diameter of a pollen grain.
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Plant reproduction
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Observations:Diameter of a pollen grain from lily –
Diameter of a pollen grain from grass –
Questions
1. State which of the flowers you have examined is wind pollinated and which is insect pollinated.
Lily – insect-pollinated
Grass – wind-pollinated.
If available, a range of flowers could be provided so students can study a range of different
flowering plants.
2. Describe for each flower, how it is adapted for pollination.
Adaptations in insect-pollinated flowers
Adaptations in wind-pollinated flowers
Bright colours
Generally green or dull colours
Often fragranced
Lack fragrance
Large petals
Small petals
Nectar produced to attract insects
No nectar
Anthers deep inside flower
Anthers usually outside flower
Stigma is inside flower
Feathery stigma lies outside flower
3. State two differences in the pollen grains of wind and insect pollinated flowers.
In wind pollinated plants pollens is light and produced in large quantities.
In insect-pollinated plants pollen is large and often sticky so it can attach to insects when they
enter the flower. Pollen is produced in smaller quantities than in wind-pollinated plants.
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Plant reproduction
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