I got to try my hand at watercolour and here is the result. I was instructed that one should start first with a flat flower...oops. Magnolias aren't flat. The only choices in flowers that day were magnolias and clovers. The clovers didn't look any flatter! I did choose a magnolia that was past its prime so that it had somewhat less definition to it. The theory didn't really result in a practical difference.
The other difficulty with magnolias is that they are white--except that the white is really a number of different shades of cream. Add to that shadows from two different lights overhead and I now saw at least four shades of shadow. An hour and a half of painting in squinting, frowning, trying to keep my yellow paint as white as possible. The shadow contains the "yellow" and a dot or two of purple as that is the opposite colour on the colour wheel. I was pleased with the overall effect. Not bad for a first attempt.