This picture illustrates the difference between pollinated and unpollinated pistil. The pistil turns into a seed pod, if pollinated. The pollinated pistil becomes enlarged. The blue circle marks 5 unpollinated flowers. The red circle marks 3 pollinated flowers. The pollinated pistils become enlarged and elongated. The longest seed pod in the red circle also shows the outline of the growing seed inside the pod. So in time, it becomes obvious which flowers got pollinated and which didn’t.