EXERCISE X 



A STUDY OF BULBS 



Material and apparatus. Bulbs of the hyacinth, tulip, onion, 

 and lily ; sharp knife. 



Bulbs of all kinds are specialized buds. They are made up of 

 a short and rudimentary axis closely incased in transformed 



. , and thickened leaves called bulb scales. 



Bulbs occur only in plants which are ac- 

 customed to long periods of inactivity, 

 and are divided into two classes deter- 

 mined by the scales. 



1. Study bulbs of the hyacinth, onion, 

 tulip, and tiger lily or Easter lily. Make a 

 drawing of each one, natural size, show- 

 ing the external characteristics. Describe 

 fully the differences in each bulb. How 

 does the lily differ from the hyacinth ? 



2. Keep a close watch for bulbils, 

 which are little bulbs found on the 



FIG. 4. Bulb of Easter lily 



parent bulb. Where do you find these located ? Are they in 

 essentially the same place in each bulb ? Make a drawing of the 

 bulbil, natural size, showing the attachment to the parent. 



3. Draw a cross section, natural size, of each bulb. What 

 differences do you observe ? Carefully examine and describe 

 the bulb scales of the hyacinth and the tulip. How does the 

 scale of the lily differ from that of the tulip and the hyacinth ? 



4. Draw a cross section of each scale. Describe in detail the 

 differences. Measure the thickness of each bulb scale. What 

 significance does the thickness of the bulb scale have ? What is 

 contained in the scales of all bulbs ? How do the scales of the 

 lily differ in arrangement and shape from those of the hyacinth 

 and the tulip ? 



REFERENCE : 



Bailey, "The Nursery Book," chap. ii. 



[28] 



