Your cameras Auto focus will also focus well on straight lines with high contrast so try to aim for edges of the leaf and re compose the shot with the half button press, You could also try focusing once then pressing the focus again so the camera has two attempts then re composing your shot
Thats all I can really chirp in with its all been covered
__________________
You cant fool all of the people all of the time, some of the time all of the people will some of time but not all of the time as some of the time all of the people will some of the time but all of the people will not all of the time
!!