A MANUAL OF BOTANY 35 



tioa. Make careful drawings showing the character of the 

 veining. 



Conclusions. From yonr knowledge of common tree and 

 plant leaves, which form of venation is the more common ? 

 Which form is best adapted to large leaves? What func- 

 tions do the veins possess as shown by the venation? 



Vernation. The unfolding of a leaf from the bud is ver- 

 nation. There are several forms: rolled, folded, twisted, and 

 coiled. Study and draw some forms of vernation. Cut off 

 twigs of as many different trees as it is possible for you to 

 obtain, place in water, and study carefully as the buds begin 

 to swell and grow. In this manner many examples of ver- 

 nation may be easily observed. Observe very particularly, 

 in this process, that the bud develops into a stem on which 

 the leaves are borne and not into a single leaf. 



Some odd forms. Some supplementary statements about 

 venation may be made. Certain leaves, like the common 

 plantain, appear to have a parallel veining, but are really 

 net-veined. Such leaves are ribbed. 



Trillium leaves are apparently a combination of parallel 

 and net venation. Another type, a form of parallel vena- 

 tion, is seen in the banana and other monocotyledons. Many 

 leaves have a marginal vein into which the netted branch 

 veins terminate. 



3. Leaf Division 



Statement. Many leaves, instead of consisting of a single 

 entire piece of expanded blade (a simple leaf), have this 

 l)lade variously divided, the lesser amount of division form- 

 ing teeth and lobes, and the greater separating the leaf into 

 few or many small })ortions called leaflets, all borne on a 

 common stem or j^d'ole. These latter forms have been 

 called compound, hnt divided is a far better expression. 

 The following leaves are easily obtainable, some from the 

 greenhouse, others when there is no snow on the ground, or 



