34 



OBJECT LESSONS IN BOTANY. 



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

 ing petiole embraces tlie stem with its winged edges like a 

 sheath. Yon can And plenty of examples of these forms. 



S3 .^4 

 Fig. 83. Eose, — stipules adnate. Fig. 84. Violet ( V. tricolor)^ — plashed stipules. 



46. Let ns now study more particularly the varying forms 

 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 



85 86 87 88 

 Fig. 85. Leaf of Coniosellnum,— tri-pinnate, with sheathing petiole. 

 Fig. 86. Leaf of Polygonum Pennsylvanicum, witli its (s) ochrea. 

 Fig. 87. Stem of Grass, with joint 0"), leaf (^), ligule (s). 

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



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

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



