154 



BUDS AND LEAVES 



surface it is channeled; it is margined if either side is bordered 

 with bladelike tissue, as in digitalis; it is laterally compressed 

 in the leaves of various species of poplar. Leaves with 

 petioles are said to be petioled; those without petioles are 



FIG. 91. Relation of Sessile Leaves to the Stem. 1, Fleabane (Erigeron 

 canadensis) normal attachment; 2, mullein (Verbascum thapsus) decurrent; 

 3, aster (Aster phlogifolius) amplexicaul; 4, bellwort (Uvularia perfoliata) 

 perfoliate; 5, sedge (Scirpus atrovirens), closed sheath; 6, grass, open sheath; 

 7, boneset (Eupatorium perfoliatum) , connate-perfoliate. 



Attachment of the Petiole to the Blade. The attachment is 

 normal when the base of the blade is attached to the petiole ; 

 it is peltate when the petiole is attached to about the center 

 of the dorsal surface, as in the nasturtium and mandrake. 



Stipules. Stipules vary greatly in different species. In 

 w r illow they are scalelike, in red clover and tulip-tree leaflike. 



