The dominant subject doe not necessarily be the largest part in the composition. This flower is dominant for two reasons:
1st: The yellow color distinct the subject from the rest of the image which is green. Yellow is also “lighter” than green and our eyes usually go to the lightest part of the photograph.
2nd: The yellow flower in in focus. I purposely chose a small f-stop to keep the subject in-focus and blow out the rest of the image.
Enjoy and happy Friday!