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Asked by anon-209836 to Annette on 13 Mar 2019.
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Annette Raffan answered on 13 Mar 2019:
So, plant roots are amazing things! To us they might seem feeble and that you can pull them apart easily. But actually they are very, very highly evolved. Roots can grow through concrete in several ways. Firstly concrete is not actually as solid as it might appear! There are lots of small cracks that your eye might not be able to see but which are perfect for roots to start to push themselves into. Once they have found a weakness, they use a huge pressure in their meristem cells to force themselves into the crack, further separating the concrete. Pressure of about 15 bar are about the limit of most plant cells. Plant cells have a cell wall which means that they can reach much higher pressure than animal cells which would just explode. They also can produce chemicals in their root cells which can dissolve concrete, probably types of acids! Also as concrete ages it cracks and warps too – as it freezes and thaws for example and roots will only too quickly exploit these weaknesses.
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Comments
Nick commented on :
Just expanding upon Annette’s answer – did you know that modern day plants that we see every day evolved from algae, which invaded the land from the ocean. The key to surviving in this environment was to convert the rocks they grew upon into food and nutrients (there was no soil at the time!). To survive on land, plants had to learn how to eat rock! As time progressed, as plants lived and died (and animals too), they decomposed and created the soil that now covers much of the Earth’s land.
The history of dirt is actually quite interesting!