BULBS, CORMS AND TUBERS. 



13 



body within composed of reserve food for supporting 

 future growth. In the case of the Tropseolum, as in that 

 of the Potato, the old tuber gives up all its reserve food to 

 the new growth, and eventually perishes; but in the case 

 of the Gloxinia it only supplies a portion of the food, and 

 has the power of absorbing additional food each year, and 



TYPES OF TUBERS. 



A, Tuber of Erythronium dens-canis. B, Tubers of AlstrQmeria. C, Tuber of an 



Anemone. 



thereby increasing in size. Tubers vary a great deal in 

 size and shape, according to the size of the plant. 



In all cases the primary object of a bulb, corm, or 

 tuber is to store up reserve food, and they may be con- 

 sidered in this respect as analogous to seeds, a means of 

 ensuring the perpetuation of the species. Under the 

 action of sunlight the sap absorbed by the roots is, by the 



