See the peak point in this leaf. The three lines that end in the peak are straigt lines,

If you want to give more curvature to the leaf you should add more intermediate points. Anyway the final peak have trhee straight lines for the reason I have explained before.
But if you want you can have TWO (or more) curvatures in the same point you can do it just adding an extra line from every line that is connecting to the peak. In this way the curvature us controlled by the position of an extra point. See the example.



The last leaf have three curvatures in the peak point what is impossible to do in the classical way.
You can bound those point to the bone that control the peak point if the figure is bone controlled to maintain the shape properly when animated.
Hope it make sense for the new users or experienced if you did not realized about this yet.
Regards
Genete