Investigating Variation in Leaf Size

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Investigating Variation in Leaf Size


How much variation will we observe between species in terms of leaf area?  How will this compare with variation within species (or between leaves of the same individual)?


The leaves of plants are adapted to maximize photosynthesis.  They are also adapted to water availability and humidity.  The size, shape and number of leaves on a given plant will reflect the conditions of its native habitat.


  • Firstly, form a group of two to three people
  • Then go outside into the garden area and collect a pair of four different types of leaves.  Try to collect a variation in leaf size.
  • After that place the leaves on a piece of squared paper (4mm²) and draw around them with a pencil.  Next count all the individual squares and record the numbers in a chart.  
  • Take the number of the squares for each leaf and multiply that number by 4.  (For example: 132 is the number of counted squares and multiplied by 4 it equals 528).
  • After calculating the area of each leaf, record the results in a table.
  • By adding the numbers together and then dividing that number by two, you will be able to calculate the mean of each leaf type.
  • Then using a ruler measure the length of each leaf but try to make it a fair test by either including or not including the small stem of each leaf.  Make sure that the measurements of length are all calculated in mm².
  • After that calculate the standard deviation of the area and then do the same for the length.
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Kettern 2

Data Collection:

Measures of Variation (Range):

Standard Deviation of Area:

Kettern 3

Then take the mean of Deviation² which is 27293 and square root it which equals 165mm².


Group 1: 510

Group 2: 165

Group 3: 256

Group 4: 69

Group 5: 46

Comparing the standard deviation of the 5 samples shows that Group 1’s sample was more than 10 times more varied than Group 5’s sample.


One of the limitations of this investigation was the sample size because more leaves ...

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