Hi Tim
I think this is a math question.
Measure the angle of the blue leaf. Say 210 degrees.
Measure the angle of the red leaf. Say 70 degrees
Subtract to find the change in angle. ~ 140 degrees

Divide by 17 to get the angle change of each leaf. About 8.24 degrees.

Array a start point on the curve, for 18 total points, which will be the base of each leaf.
...

I'm reminded of ArrayGem and variable pitch helix.

- Brian

A .3dm file would be convenient.