Lily pads don't remember direction

I am playing in survival mode and found a swamp biome.

The lily pads seem to have spawned in with some of the facing all different directions. However when I mine one and place it down it doesn't seem to remember the direction it originally had.

For example, I mined one that spawned in facing east. When I place it down it faces north. So I mined it and placed it down again. This time it faced north. On the 5th try it faced south. I have done this about 20 times with the same lily pad and I have seen it facing north, south and east and west on different water source blocks.

However if I repeatedly mine and place the same lily pad on the same water source block, it places consistently facing one of the directions. I have observed it placing north, east, south and west consistently if the same destination water source block is chosen repeatedly.

How it chooses which direction seems arbitrary, I cannot observe a pattern...