As well as the above person saying it’s small, thin and flexible, grass also grows from its base, whereas other plants usually grow from the top. This means if anywhere above the growth area is damage, eaten or cut, the blade of grass will continue to grow. It’s why cows and similar animals can graze on fields and the field will continue to be green (and spect if it gets waterlogged and the cows’ hooves can disturb the roots of the grass)
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