120 SCARS OF BUD-SCALES [CH. 



numbers of groupings referred to are useful in many cases 

 of diagnosis. 



Most twigs exhibit a series of crowded scars at the 

 base, usually thinner and smaller than those along the 

 length, and in many cases provided with fewer and finer 

 leaf- trace scars than the normal. -These narrow and 

 crowded scars are those of the bud-scales which enveloped 

 the present twig when it was in the bud state, and before 

 it had elongated to a shoot, and they therefore mark the 

 limit of the previous season's growth (Figs. 46 and 47). 

 Moreover these ring-like groups of crowded bud-scale scars 

 persist for several, or even many years, and if we search 

 back along the older twigs and branches of a normally 

 grown specimen, they may be found clearly delimiting the 

 successive annual growths of the branch. Every stretch of 

 ordinary nodes and internodes, reaching outwards or up- 

 wards from one of these groups of scale-scars to the next 

 above, marks the length of extension of the branch for 

 one year ; and, of course, the length of clear twig extend- 

 ing beyond the last group of scale-scars to the terminal 

 bud marks the growth of the season just past. When the 

 present terminal bud unfolds next spring, its bud-scales 

 will leave similar scars, closely crowded, because the inter- 

 nodes between bud-scales do not elongate, and will in like 

 manner occupy the base of next year's twig when the 

 seasonal growth has been completed. 



It will now be intelligible why the leaf-scars are so 

 crowded on the so-called spurs, or dwarf-shoots of many 

 trees (Fig. 51): it is because the internodes between the 

 leaves on such dwarf-shoots elongate little, if at all, more 

 than do those between the bud-scales which covered them 

 the previous year. In many trees these dwarf-shoots go 

 on giving rise to further dwarf-shoots year after year, each 

 season's growth in length being little, if any, greater than 



