I have grown some sunflowers either side of a patio door - facing south.

I was really quite cheesed off that instead of facing south and be visible -
the flower heads decided that they were going to face north : ie toward the
wall.

I then realised that when sunflower heads follow the sun: they don't actually
have "eyes" - they are following the source of the heat.

I think that my sunflower had realised that rather than waste energy following
the sun: it was much better to face the wall all day, and every day: and get
the heat from the brick wall !!