114 



General Botany 



A hulh is a fleshy underground bud, made up of a short stem 

 covered with several layers of thick scales in which food is stored. 

 Tulips, hyacinths, and onions are commonly propagated by means 

 of bulbs. Some kinds of onions also produce small bulbs 

 (" sets ") in place of flowers, and some hhes develop them in 

 the axils of their leaves. 



By planting bulbs of the tulip in autumn, we can have flowers 

 early in the following spring, whereas if we planted the seeds, we 

 should have to wait several years for flowers. It requires two or 

 three seasons of photosynthesis to accumulate sufficient food for 

 flower production. Furthermore, tulips do not grow well except 

 in a very moist climate, and the development of large, vigorous 

 bulbs is impossible in most parts of the United States. For this 



reason nearly all our tulip 

 bulbs are brought from Hol- 

 land. The importation of 

 bulbs from countries where 

 they grow particularly well 

 is an important industry and 

 enables us to have many 

 flowers which cannot be as 

 successfully propagated in 

 our climate. 



Tubers are the enormously 

 thickened portions of short 

 underground stems. The 

 potato and the Jerusalem 

 artichoke are the most fa- 

 miliar plants forming tubers. 

 The scale leaves of the or- 

 dinary rootstock are in tu- 

 bers reduced to ridges, and 

 the buds themselves to mere 

 points. The scales and buds 



Fig. 63. Dasheen and edible corms produced by 

 it. The dasheen is related to the common "ele- 

 phant's ear" or Caladium, and is extensively 

 grown in the tropics for food. In the states 

 along the Gulf Coast it is being introduced as a 

 food plant. 



