ITS SUBTERRANEAN MODIFICATIONS. 



Ill 



179. The regular plan of increase and ramification already de- 

 scribed prevails in these extraordinary, no less than in the ordi- 

 nary, forms of the stem. They grow and branch, or multiply, by 

 the development of terminal and axillary buds. This is perfectly 

 evident in the rhizoma and tuber, and is equally the case in the 

 corm and bulb. The stem of the bulb is usually reduced to a mere 

 plateau (Fig. 146, a), which produces roots from its lower surface, 

 and leaves (the exterior of which are reduced to scales) from the 

 upper surface. Besides the terminal bud (c), which usually forms 

 the flower-stem, lateral buds (b) may be produced in the axils of 

 the leaves or scales. One or more of these may develope as flow- 

 ering stems the next season, and thus the same bulb survive and 

 blossom from year to year (as is the case with the Tulip, Hya- 

 cinth, &c.) ; or these axillary buds may themselves become bulbs, 

 feeding on the parent bulb, which in this way is often consumed by 

 its own offspring, as in the Garlic (Fig. 147) ; or, finally separat- 

 ing from the living parent, just as the bulblets of the Tiger Lily 

 fall from the stem, they may form so many independent individ- 



t 



uals. So the old corm of the Crocus (Fig. 148) produces one or 

 two new ones (a) near the apex, and gradually dies as they devel- 



FIG. 145. Section of a tunicated bulb of the Onion. 



FIG. 146. Longitudinal section of the bulb of the Tulip, showing its stem (a) and buds 

 (b, c). 



FIG. 147. Bulb of the Garlic, with a crop of young bulbs. 



FIG. 148. Vertical section of the corm of Crocus : a, new buds. 



FIG. 149. Vertical section of the corm of Colchicum, with the withered corm of the preced- 

 ing (a), and the forming one (c) for the ensuing'year. 



