164 



BOTANY OF THE LIVING PLANT 



to those of the previous year. Most of these plants form their leaves 

 first, and they have the advantage of developing more rapidly than in 

 germination, as they can draw on the store already in hand. But some 

 flower at once, even before their vegetative leaves are fully formed, 

 as in the Christmas Rose {Helleborus), the Crocus, and Snowdrop. 



For the disposal of their store a slight distension of the tissues is 

 often sufficient in these herbaceous perennials. This is seen in the 



Pc-rennial slock of Ins. 



Fig. 122. 



5urci.ssi\'C' yearly growtlis 



(.\fter Figiiier.) 



Iris (Fig. 122), where the short stock grows onwards from vear to vear, 

 bearing fresh leaves each season and axillary buds, and storing each 

 year's surplus in the massive stem. In other cases the various parts 

 may be considerably changed in their proportions. Thus the roots 

 of the Dahlia are swollen to hold inulin (Fig. 123), and root-storage is 

 also seen in the native Orchids, in Ranunculus Ficaria, and in Spiraea 

 filipend-ula. But it is -more frequently the stem, or rhizome as it is 

 called when underground, that is distended for storage. The familiar 

 corm of the Crocus is simply an abbreviated upright stem, a given 



