34 TREES OF THE NORTHERN UNITED STATES 
the midrib, bringing the two halves together. Peach 
Plicate: folded several times lengthwise,like a fan. Birch. 
Convolute: rolled edgewise from one edge to the other. 
Plum. Involute: both edges rolled in toward the midrib 
on the upper side. Apple. Revolute: both edges rolled 
backward. Willow. Obdvolute: folded together, but the 
opposite leaves half inclosing each other. Dogwood 
