50 
STUDIES OF PLANT LIFE. 
(6) Desirable material for plant stem modifications: 
stems of timothy hay, wheat, or oats, Morning 
Glory and Virginia Creeper, Rose and Cactus, 
Hawthorn or Honey Locust, Potato, Onion, some 
rhizome, and any solid bulb. 
. Stem of a grass or grain. 
How do the nodes of these stems compare with those 
of other forms already studied? Is the stem hol- 
low or solid? Why? 
. Morning Glory or Climbing Bean. 
Ts the stem rigid enough to support itself in an up- 
right position? If not, how does it grow? Why? 
Do they always twine about a support in the same 
direction? Why? Sketch. 
Virginia Creeper and Grape-vine. 
How do these accomplish climbing? These slender, 
more or less coiled stem modifications are tendrils. 
How do they differ? How and why are the ten- 
drils coiled between the plant and its support? 
Draw a portion of a stem with its tendrils. 
. Hawthorn or Honey Locust and Rose. 
What is the evidence that thorns are modified 
branches? What is their purpose? How do the 
prickles of the rose differ from the thorns as to 
origin, size, and distribution. Make sketches. 
. Cactus, Potato, some rhizome, and any solid bulb. 
Are leaf scars, buds, or any form of leaf apparent 
in each? What is the purpose of the form of 
stem in each of these plants? Draw and name 
parts. 
Onions or Lily bulb in longi-section. 
Where is its stem? Are its internodes long or 
short? Is the bulb all stem structure? In what 
