SECTION 7.] 



SPECIAL LEAVES. 



63 



Beans, give faint indications of service as foliage also, chiefly in vaiu. Slill 



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



into the first efi&cieut foliage. Compare 



11, 22-30, and the accompanying figures. 



160. Leaves as Bud-Scales serve <o 

 protect the forming parts witliin. Hav- 

 ing fulfilled this purpose they commonly 

 fall off when the shoot develops and 

 foliage-leaves appear. Occasionally, as 

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

 scales to loaves, which reveals the nature 

 nf the former. Tlie Lilac also shows a 

 gradation from bud-scale to simple leaf. 

 In Cornus florida (the Flowering Dog- 

 wood), the four bud-scales which tli rough 

 the winter protect the head of foruiing 

 flowers remain until blossoming, aud then the base of each ^rows out into 



Fig. 170. Series of bud-scales aiul foliage-leave.s from a developing hud of the 

 Low Sweet Buckeye (/Esculu.s parviflora), sliowiiis nearly complete gradation, from 

 A scale to a componnd leaf of five leaflets; and that the scales answer to reduced 

 petioles. 



t'lG. 171. Shoot of common Barhcrry, showing transition of loliage-leavcs t<? 

 "{lines. 



