When I did these marks I did not know or did not remark that I was trying to reproduce the colours from the leaves in the photo below. Or I knew I was doing it but not knowing that it would be now, a much better result for a more advanced exercise.
Exercise 4 :: mixing colours from three dimensional objects :: watercolour
Drawing is not my strongest skill but with aquarelle was I was able to match the colours I saw on this lemon. When I did this, there was no natural light and I didn't take a picture to compare.