STORKS AGRICULTURAL EXPERIMENT STATION. 321 



in a condensed condition. The bud-scales are modified leaves which 

 protect the parts within from mechanical injury and from loss 

 of moisture,, but are of little value as a protection against cold as 

 is often supposed. At falling they leave a ring or band of scale- 

 scars marking the limit of each year's growth. These bands often 

 remain distinct for many years (see twig of Beech p. 429) 

 and by counting their number the age of the branchlet may be 

 estimated. Thus it can be readily seen that the figure of the 

 Horse-chestnut represents growth made during three years. Each 

 year a ring of new wood is formed just underneath the bark, and a 

 count of the number of these annual rings between the central pith 

 and the bark, as seen in a cross section of a branch or trunk, 

 will likewise give the age of the part investigated. The uppermost 

 buds of a year's growth are generally the largest and most likely 

 to develop into branches the following spring. In some species, 

 such as many of the Evergreens, and the Carolina Poplar (p. 395) 

 for example, the branches coming from these more vigorous buds 

 form regular whorls along the trunk at the upper part of each 

 year's growth and afford for such species a third means of esti- 

 mating the age. Certain of the buds do not continue the growth 

 of the twig but form flowers which develop into fruit. Where the 

 individual fruit (in the Horse-chestnut the fruit cluster) was 

 attached, a fruit-scar is left and these fruit-scars furnish evidence 

 of the amount of fruit produced in previous years. 



In some species, such as the Black Birch (p. 415) and the 

 cultivated Cherry (p. 503), a sharp distinction can be drawn 

 between rapidly-grown long shoots which have elongated inter- 

 nodes and continue the growth of the twig and slowly grown 

 short spurs which have greatly abbreviated internodes and crowded 

 leaf -scars. The fruit-spurs of the Apple (p. 487) and Pear 

 (p. 485) are of this latter type. 



Of the distinctive characters given under the heading twigs may 

 be mentioned the relative thickness, whether stout or slender, the 

 presence or absence of thorns or prickles, the color, the taste as 

 indicated under the discussion of the bark, and the character of 

 the surface, whether smooth or more or less covered with hairs. 

 Twigs are called hairy when the hairs are individually distinct, 

 downy when they are fine and numerous, and woolly or cottony 



