THE FLOWERING PLANT LEAVES 365 



base to the apex of the blade ? Have you any 

 specimens in which a number of large veins 

 of about the same size run lengthwise of the 

 blade, thus illustrating longitudinal or par- 

 allel venation ? Make a list. In which leaves 

 do the most of the large veins unite to form a 

 network, thus showing reticulated or netted 

 venation? Make a list. Jn a third hst put 

 all of the leaves in which the veins radiate 

 from the base to the margin of the blade, ex- 

 amples of radiate, digitate, or palmate ve- 

 nation. Can you trace any relation between 

 the venation and the outline of the blade? 

 Are the veins composed of more or less firm 

 tissue than the rest of the blade ? Do the veins 

 form a support for the other tissues ? Hold a leaf 

 between yourself and the light, and look to see 

 if the veins near the margin are so arranged as 

 to offer resistance to tearing the soft tissues of 

 the blade. Do you find any large areas into 

 which the veins do not penetrate ? 

 3. The stipules. — What is their shape ? What va- 

 riations in shape ? How are they attached to 

 the petiole? In what respects do stipules re- 

 semble the leaf- blade ? 

 Draw each of the simple leaves, showing its exact 

 shape and venation. 



Examine the compound leaves in like man- 

 ner and draw each. 



Can you arrange any of the specimens in a 

 series to show how compound might be derived 

 from simple leaves ? 



