THE LEAVES. 



99 



leaf base is always present, but either the leaf stalk or the 

 leaf blade or both may be absent. The leaf blade is ordi- 

 narily winged; indeed it is for this reason that it received the 

 name "blade." Either the stalk or 

 the base or both may also be winged. 



124. I. The leaf base. — The leaf 

 base is generally enlarged so as to 

 form a sort of cushion by which it is 

 attached to the stem. When a broad 

 base is attached over a considerable arc 

 of the circumference of the stem, so 

 that it encircles it more or less, the 



Fig. 87. Fig. 88. 



Fig. 87. — Leaf of Ranunculus Ficaria. b, leaf base; p, petiole, or leaf stalk; /, 

 ^ lamina or leaf blade. Natural size. — After Prantl. 



Fig. 88. — A leaf of a grass, with part of stem to which it is attached, j, sheath (leaf 

 base) attached all around node k of the stem A, h\/^ blade ; /, the ligule, an outgrowth 

 from the surface. Natural size. — After Frank. 



base is sa,id to be sheathing (fig. 87). In grasses, for ex- 

 ample, the leaf base is attached over the entire circumfer- 

 ence of the stem, and enwraps it completely for a considerable 

 distance above the node (fig. 88). 



125. Stipules. — ^The leaf base frequently branches. These 

 branches, commonly two in number, are called stipules 

 (fig. 89). They vary from slender, awl-shaped bodies to 



