PLANT ORGANS AND ORGANISMS 
119 
the two sides are brought together as in the oak, it is conduplicate; 
when rolled inward from one margin to the other, as in the Wild 
Cherry, it is convolute; when rolled from apex to base, as in Ferns, it 
is circinate; when folded or plaited, like a fan as in Ricinus, Maples, 
Aralias, etc., it is plicate; if rolled inward from each margin, as the 
leaf of the common Violet, involute; when rolled outward from each 
margin as Rumex, revolute. The inner surface is always that which 
will form the upper surface when expanded. 
Fig. 55. — Stereogram of leaf structure. Part of a veinlet is shown on the right. 
Intercellular spaces are shaded. ( From Stevens.) 
The Complete Leaf.- — The leaf when complete consists of three 
parts, lamina , petiole, and stipules. The lamina or blade is the expan- 
sion of the stem into a more or less delicate framework, made up of 
the branching vessels of the petiole. 
The petiole is the leaf stalk. The stipules are leaf-like appendages 
appearing at the base of the petiole. 
The leaf of the Tulip Poplar or Liriodendron affords a good exam- 
ple of a Complete Leaf. 
