FORMS OF THE PETIOLE. 



33 



Fig. 80. Amplexicaul leaves of Aster laevis. 



Fig. 81. Perfoliate leaves of Belhvort {Uvularia perfoliata). 



Fig. 82. Connate leaves of Honeysuckle {Loaicera sempervirens). 



43. In Fig. 82 (Trumpet Honeysuckle) the leaves placed 

 opposite are joined together by pairs, base to base. Sucli 

 are connate leaves. 



44. The forms of the petiole, when the petiole exists, are 

 also various. Generally, it is merely a rounded, slender 

 stem, but you will often find it flattened. Have you ever 

 noticed the structure of the Aspen (Poplar) leaf, which so 

 easily flutters in the gentlest breeze ? Its petiole is flattened 

 vertically, so that its edges turn sky-ward and earth- ward. 

 Snch a form of leaf-stalk is called comjpressed^ and it must be 

 very nicely balanced in order to hold the blade at rest. 



48. Wlien are leaves said to be connate ? 



44. What is tlie usual form of the petiole ? Carefully describe the petiole 

 of the Aspen. 



2* 



