104 INTRODUCTION TO BOTANY 



5. Which bud of each year's growth is usually strongest ? 



6. How many wood rings would a cross section of fig- 

 ure 88 show at i l ? at i n ? at i s ? Why would these rings 

 differ in size ? 



7. What would have been the effect upon the wood rings 

 of figure 88 of pulling off most of the leaves above b. se as. 

 fast as they appeared ? 



97. The record ; fruit scars. Fruit scars of the same species 

 are often quite unequal in size, the smaller ones marking the 

 positions of unsuccessful fruits and the larger ones of fruits 

 which grew to maturity. Sometimes in mixed buds the young 

 flowers may be destroyed by frost as the bud opens, and in 

 that case it develops much like an ordinary leaf bud, leaving 

 no fruit scar. 



In order to learn just the course which a bud follows dur- 

 ing its development throughout a year or more, it should be 

 marked by tying a bit of twine or winding a bit of fine copper 

 wire very loosely just above or below it. Sketches like fig- 

 ures 83 and 84 should then be made and notes taken from 

 time to time, whenever decided epochs in the history of the 

 bud occur. 



98. The record; leaf scars. Among the most prominent 

 markings on a twig several years old are the roundish, or 

 horseshoe-shaped, areas known as leaf scars (figs. 77 and 78, 

 sc and 90, sc). These mark the positions where (at the base 

 of each leafstalk) a waterproof layer was formed when the 

 leaf was shed (sect. 81). Some of the things which can be 

 learned from the study of leaf scars are the number, posi- 

 tion, and arrangement of leaves on the shoot for several 

 years back,, the relative sizes of the leaves, and the mode of 

 bud-bearing of the species studied that is, whether there 

 were accessory buds or whether the buds were all axillary. 

 On careful examination of any large leaf scar, as that of the 

 ailanthus, the horse-chestnut, or the coffee bean, it is seen to 

 be dotted with a considerable number of minute projections. 

 These mark the course of the fibrovascular bundles from 



