How can you find the surface area of a leaf?

Answer 1

ANSWER 1

You might divide the leaf into small rectanges (actually, reasonable approximations of rectangles), and measure length x width for each one. The smaller each rectangle (the narrower, to be precise), the more accurate will the result be.

ANSWER 2

The answer above is correct, but it will take a long time to produce a high degree of accuracy.The best method depends on the accuracy required. If you require accurate and precise results, use a scientific instrument that's specially designed to measure the area of leaves. E.g. AM300 Leaf Area Meter

My AM300 can store the image, and will analyse it to measure all sorts of useful parameters, like perimeter. I need a lightweight instrument which I can carry for hours, and it only weighs 1.8kg . Other models which are called 'portable' weigh 6.8kg!

If you do not require a high degree of accuracy, you can draw around the leaf, then cut out and weigh the paper. By comparison to the weight of a known area of the same paper, you can calculate the area of the leaf. However, when using methods which involve cutting paper, you must cut around the perimeter extremely carefully. Similarly, you must be highly accurate when weighing. I am not sure that paper - even heavy paper - is heavy enough to make the relative error <0.5%.

You can opt for a method where you draw around the leaf on graph paper, then estimate how many grid squares are included in the area. However, grid squares that are partly included in the area must be approximated so introduce inaccuracies.

I have used software called imageJ to draw an irregular polygon on a photo of my leaf. I investigated C.hirsuta leaves, which are a similar size toArabidopsis, so it was possible to click a enough points on the image to accurately trace the perimeter, without it taking hours. To trace the perimeter of a larger leaf, you will have to make hundreds of clicks. By my experience, this will take a morning per leaf!