66 



LEAVES. 



[section 7. 



by sticking fast to very viscid glaiuls at the tip of strong bristles, aided 

 by adjacent glaud-tippcd l)ristlcs wliich bend slowly toward the captive. 

 The use of such adaptations and ()j)eratious may be explained in anothci 

 place. 



§3. STIPULES. 



174. A leaf complete in its parts consists of blade, leaf-stalk or petiole, 

 and a pair of stipules. But most leaves have either fugacious or minute 

 stipules or none at all ; many have no petiole (the blade being sessile or 

 stalkless) ; some have no clear distinction of blade and petiole ; and many 



of these, such as tliose of the Onion and 

 all phyllodia (166), consist of petiole only. 

 175. The base of the petiole is apt to 

 be broadened and flattened, sometimes 

 into thin margins, sometimes into a sheath 

 which embraces the stem at the point of 

 attachment. 



176. Stipules are such appendages, either wholly or partly separated 

 from the petiole. When quite separate they are said to he free, as in Fig. 

 112. When attached to the base of the petiole, as in tlie Rose and in 



Fig. 177. Leaf of Red Clover: st, stipules, adhering to the base of ;>, the petiole; 

 b, blade of three leaflets. 



Fig. 178. Part of stem and leaf of Prince's-Feather (Polygonum orientale) with 

 the united sheathing stipules forming a sheath or ucrea. 



Fig. 179. Terminal winter bud of Magnolia Umbrella, natural size. 180. Outer- 

 most bud-scale (pair of stipules) detached. 



