But this summer seeing all the greenery turn yellow and die I know it's probably just a matter of speaking since you use 'all' while you're likely well aware i

But this summer seeing all the greenery turn yellow and die I know it's probably just a matter of speaking since you use 'all' while you're likely well aware it's not really 'all', but with respect to the dying: a lot of these plants aren't dead yet. In case of grasses the root system is still ok, similar for roots and part of the stem for herbs/trees. It works like a first aid in coping with drought: get rid of the stuff which evaporates the little water which is still there, so that by the time water is available again it might not too late to recover. Actually depending on the plant there are even earlier stages of such mechanisms; for example the leafs of some plants have a pale, almost white, underside and when drought kicks in the'll turn there leaves upside down to reflect more light and absorb less heat.