34 



OBJECT LESSONS IN BOTANY. 



45. A winged petiole is flattened horizontally. A sheath- 

 ing petiole embraces the stem with its winged edges like a 

 sheath. You can find plenty of examples of these forms. 



fig. 83. Eose, stipules adnate. Fig. 84. Violet ( V. tricolor), gashed stipules 



46. Let us now study more particularly the varying forma 

 of the stipules. We have already defined them. (See Les- 

 son I., 4.) Here is seen the leaf of a Rose and of a Pansy 

 (Figs. 83, 84), both with quite showy stipules. The former 



Fig. 85. Leaf of Conioselimun, tri-pinnute, with sheathing petiolo. 



Fly. 86. Leaf of Polygonum Penn&ylvanicntn, with its () cchrea. 



Fig. 87. Stem of Grass, with joint (./), leaf (I), ligule () 



Fig. 88. Leaf of Pear-tree, with slender stipules. 



45. What difference between a winged and compressed petiole ? Can you 

 describe a sheathing petiole 1 Give examples of these three forms. 



