Clever Tulips

I wonder how anything underground knows which way is up. Gravity I suppose,  but it is incredible whatever they use. Those tulips give a new meaning to 'doing a Uey'

Yep, not read about it before, but it's called gravitropism. The root tips of plants have cells called statocytes which contain grains of starch called statoliths. The statoliths sediment to the bottom of the cells under gravity, which sends a signal to other cells to unevenly distribute the growth hormones in the root tip, so one side of the root grows faster than the other, causing it to curve downwards.