FORMS OF THE PETIOLE. 



33 



Fig. 80. Amplexicaul leaves of Aster laevis. 



Fig. 81. Perfoliate leaves of Bellwort {Uvulana perfoliata). 



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



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

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

 are connate leaves. 



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

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

 stem, but you vill often iind it flattened. Plave you ever 

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

 easily flutters in tlie gentlest breeze ? Its petiole is flattened 

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

 Such a form of leaf-stalk is called compressed., and it must be 

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



43. When are leaves said to be connate ? 



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

 of the Aspen. 



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