114 LABOKAT011Y AND FIELD EXERCISES 



and roots ? Are there lateral and terminal buds ? 

 How does the terminal bud of ferns differ from that 

 of higher plants ? Can you think of reasons for the 

 differences observed ? Are there lateral branches, 

 and if so, have they a definite arrangement ? Observe 

 the ramenta, or brown scales, characteristic of ferns 

 on the stem, leaf bases, and young leaves. What is 

 the probable function of these ramenta as the ter* 

 minal bud unfolds in the spring ? 



2. Leaves. 



a. Mature leaves. Contrast the mature leaves of ferns with 



those of higher plants in size, form, texture, and 

 venation. What are the distinctive characteristics 

 of fern leaves accessible to you, and of fern leaves 

 known to you, as compared with those of higher 

 seed plants ? Study the mode of venation and the 

 termination of the veins, comparing ferns and some 

 common seed plants in this respect. 



b. Young leaves. Study the growth and form of young 



leaves of the terminal bud. What are the distinctive 

 characters of young fern leaves as regards form and 

 method of growth ? 



3. Roots. Study the mode of brandling of roots. Is there 



any distinctive feature which characterizes ferns in 

 this respect as compared with higher plants ? Deter- 

 mine also the origin and distribution of roots on 

 the stem. 



4. Adjustments to the environment by tropisms (see the 



text, Part I, and earlier laboratory work on tropisms). 

 Determine the tropisms of the stem, roots, and leaves 

 of ferns and apply proper terms to indicate the nature 

 of stimulus and response, for example, protropic, 

 apotropic, and diatropic. 



