18 REPRESENTATIVE PLANTS 



the delicate structures near the center of the bud (tiny 

 leaves and possibly flowers distorted and crowded upon the 

 growing point of the stem). \Vhat then does the winter bud 

 consist of, and what will it become during the next season's 

 growth ? What, again, may be the purpose of the scales with 

 their various coatings? What provision has the jdant to 

 insure continued growth if the apical bud is destroyed ? 



Caution. Mistakes are comnjonly made here. Consult a 

 good reference book (up to date) on the use of the bud 

 covering. Make drawings showing an apical bud and a 

 lateral bud, natural size (m), also a bud section (in). 



2. Leaf scars. Examine the surface below the buds for 

 peculiar scars or marks. What are their shape and size 

 compared to the twig diameter? Observe carefully the 

 surface of the scars. What do you find? What maybe 

 the causes of the scars and the scar markings? 



Draw a scar in relation to the bud above it (m). 



3. Lenticels. On the surface of the twig look for small 

 marks, scattered here and there, varying much in number, 

 size, and shape, in different twigs. These are the lenticels or 

 air pores, and are caused by the stretching of the epi- 

 dermis in growth. Same use in part as the stomates (in leaf 

 study). 



4. Zones. In a twig of some length or of several years' 

 growth look for peculiar bands of small scars, at irregular 

 intervals along the twig. These are the zones of scars. 

 What explanation have you to offer for their production and 

 irregular distribution ? What relation may there be between 

 zone number and age or years' growth? Compare the 

 hickory twig with as many others as possible, for the pur- 

 pose of shedding light on the zone question. An apple twig 

 is very fine for zone study. 



Twig drawing. Make a drawing of the whole twig, 

 natural size, showing buds, scars, lenticels, and zones, and 

 write a clear description of the same. 



