Study the way that angles and proportions change on a foreshortened flower. Petals and the negative spaces between petals that connect to the short axis (top and bottom) of a foreshortened ellipse keep their width but become shorter. Petals and negative spaces between the petals that connect to the long axis (sides) of a foreshortened ellipse keep their length but become narrower. Because the proportions of the top and bottom petals change, they may appear to get wider while the side petals appear to get longer. This is an illusion as you can see by following the red lines in the illustration on the right.
The diagrams below highlight subtleties in these changes. In the first column, I have taken a simplified flower shape and squished it to replicate angles seen in foreshortened flowers. I then rotate the flower shapes so that the petals point to different points around the circle and re-squish the flower. Finally I rotate foreshortened (squished) flowers so that the long axis of the ellipse is no longer horizantal. As you study this post, it will help to hold a paper flower model that you can tilt and study. Download one here.
Click on the first illustration to start a step by step sideshow.
As you foreshorten flowers, notice changes in petal width and length. Petals closer to the vertical position get shorter but maintain their width. Petals closer to the horizontal position get narrower but maintain their length.
Now observe the negative spaces between the petals and the length of the arc segment between each petal. Arc segments on the top or bottom of the ellipse are longer with wider petal angles than on the sides.
Flowers can rotate on three axes. The flower may rotate within the circle as we see in the first row. The flower may tilt toward or away from you as we see in the subsequent three rows. Finally the axis of the foreshortened oval may also tilt as in the last row.