64 GROWTH AND WORK OF PLANTS 



tinue the growth, the coming year, of the main shoot, and that the 

 lateral shoots will be subordinate in size. The buds are well 

 protected by brown, overlapping, external scales and a sticky, 

 varnish-like substance, which covers them. If the 

 scales are removed one by one their position and rela- 

 tion can be seen. They occur in pairs, the two of a 

 pair being opposite, and each pair alternates with the 

 pair above and below. Some of the buds are leaf 

 buds while others are flower buds. As the buds open 

 in the spring it can be seen that the leaves have a 

 similar relation to each other, and to the scales, except 

 that they are farther apart. As the scales fall away 

 they leave transverse lines on the shoot, which are 

 crowded and in the form of ringmarks. These are 

 the scale scars. They mark the end of one year's 

 growth of the shoot and the beginning of the next. 

 By observing these ring scars on the shoot the age of 

 the shoot can be determined for several years back. 

 If the shoot is cut obliquely at different ages it will be 

 seen that the annual rings indicate the same age of 

 the shoot as the scale scars do. Lateral buds. The 

 lateral buds are opposite and arise above the leaf 

 scars. The larger buds are on the last year's growth, 

 and those nearer the terminal bud are the larger and 

 will develop into lateral branches. Those buds which 

 do not ordinarily develop into shoots are latent buds, 

 and if the terminal and larger lateral buds are re- 

 moved by cutting off the part of the shoot which bears 

 them, can develop into shoots. The leaf scars. The 

 leaf scars are large and shaped something like the 

 Fig 59 bottom of a horse's foot with a horseshoe and nails. 

 Shoot of horse The series of pits (bundle scars) mark the position of 



chestnut. . 



the vascular bundles which extend from the stem into 

 the petiole of the leaf. Scattered over the surface of the shoot 

 are numerous minute, grayish or dull white elevations, the 

 lenticels. 



