The Stems of Plants 



113 



increases in thickness each year, the upright branches used as 

 food become larger and more succulent. It is this store of food 



J. E. Weaver 



Fig. 62. A common grass {Redfiddia) in the sand hills of Nebraska, showing parts of the 

 extensive system of rootstocks and roots. Sections divided into one-foot squares. The 

 underground parts of the plant were carefully dug out, and their horizontal extent and 

 depth in the soil were found to be as shown in the illustration. 



and the readiness with which the rootstock sends up shoots, that 

 make the bindweed and perennial morning-glories so difficult to 

 eradicate from cultivated fields. 



A short, upright, fleshy rootstock, like that of the jack-in-the- 

 pulpit, caladium (elephant's ear), or gladiolus, is called a corm. 

 Corms contain large amounts of food, and by the development 

 of their lateral buds may serve to reproduce the plant as well as 

 to carry it over the winter. The dasheen, a tropical plant which 

 resembles the caladium, and which has recently been introduced 

 into the United States, has an edible corm that is an important 

 source of food (Fig. 63). 



