STEMS AND THEIR APPENDAGES. 



63 



which they are developed. Leaves are generally formed 

 by the elongation and expansion of the ligneous bundles 

 of tissues, the interspaces being filled with cellular 

 matter {Parenchyma), of green or greenish color. 

 That the woody part or frame-work of the leaf is of 



Fig. 21.— LEAF OF LILAC. Fig. 83.— LEAF OF BEECH. 



the same nature as that of the branch or stem is shown 

 m the readiness with which many kinds produce both 

 buds and roots; consequently, leaves may produce stems 

 as well as stems leaves. 



