EXPLANATION OF TERMS 



/ft 



1 2 3 



Leaf-outlines. — 1. Awl-shaped. 2. Linear. 3. Lanceolate. 4. Oblong. 

 5. Elliptic. 6. Oval. 7. Ovate. 



Leaf-outlines and Extremities. — 1. Oblanceolate, with acute apex. 

 2. Spatulate, with obtuse apex. 3. Wedge-shaped, or cuneate. 4. Acuminate. 

 5. Heart-shaped at base. 6. Clasping. 



An ordinary leaf consists of a usually flat portion, the blade, 

 joined to the stem by a leaf-stalk or petiole. When there is no 

 petiole, the leaf is said to be sessile on the stem. Stipules are out- 

 growths from the base of the petiole. They may be small and 

 scale-like, or larger and leaf-like. They are often absent. 



As to position, leaves are clasping, when the base more or 

 less surrounds the stem horizontally; sheathing, when the base 

 of the blade or petiole forms a vertical sheath around the stem; 

 alternate, when not opposite to each other but arranged singly at 

 different heights ; opposite, when two grow from the same node 

 at opposite sides of the stem ; whorled, when several are arranged 

 around the stem like the spokes of a wheel. 



Simple leaves have a blade of a single piece. Compound leaves 

 are divided to the midrib into separate parts, called leaflets. 

 Pinnately compound leaves have the leaflets arranged along the 



