SECTION 7.] 



SPECIAL LEAVES. 



63 



Beans, gire faiat indications of service as foliage also, chiefly in vain. StiU 

 others, as in the Pumpkin and Flax, having served for storage, develop 



into the first efficient foliage. Compare 

 11, 22-30, and the accompanying figures. 



166. Leaves as Bud-Scales serve to 

 protect the forming parts vifithiu. Hav- 

 ing fulfilled this purpose they commonly 

 fall oif vrhen the shoot develops and 

 foliage-leaves appear. Occasionally, as 

 in Fig. 170, there is a transition of bud- 

 scales to leaves, which reveals the nature 

 of the former. The IJilac also shows a 

 gradation from bud-scale to simple leaf. 

 In Comus florida (the Flowering Dog- 

 wood), the four bud-scales which through 

 the winter protect the head of forming 

 flowers remain until blossoming, and then the base of each grows out into 



Fio. 170. Series of bud-aoales and foliage-leaves from a developing hud of the 

 Low Sweet Buckeye (^Esoulus parviflora), showing nearly complete gradation, from 

 1 scale to a compound leaf of five leaflets; and that the scales answer to reduced 

 petioles. 



I'm. 171. Shoot of common Barberry, showing transition of ibliage-leaves to 



npillOS. 



