102 



PRACTICAL BOTANY 



FIG. 87. Leaf scar of horse- 

 chestnut 



/u, scars marking position of fibro- 



vascular bundles ; len, lenticels. 



Twice natural size 



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



that case no fruit scar will be left at the end of the season, 



the bud developing much like an 

 ordinary leaf bud. 



The only way in which one can 

 become thoroughly familiar with the 

 course of development of shoots, 

 flowers, and fruits from buds is to 

 mark some buds like that shown at 

 A in Fig. 76. This may be done by 

 tying a bit of twine loosely above 

 each bud ; its history is then to be fol- 

 lowed for at least a year and recorded 

 by means of frequent drawings. 



92. The record; leaf scars. A leaf 

 scar is the place which was occupied 



by the base of the leafstalk while it remained attached to 



the shoot. Some of the things which can be learned from the 



study of leaf scars are the number, 



position, 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 spe- 

 cies studied, i.e. whether there 



were accessory buds, or the buds 



were all axillary (Figs. 75 and 85). 



On careful examination of any large 



leaf scar, as that of ailanthus, horse- 

 chestnut (Fig. 87), coffee bean, it is 



seen to be dotted with a considerable 



number of minute projections, fv. 



These mark the course of the fibro- 



vascular bundles from the leaf into 



the stem. In leaves of dicotyledons 



there are usually about as many such dots on the scar as there 



were principal veins in the leaf. Why ? 



B 



FIG. 88. Lenticels, wild black 

 cherry 



A, soon after the destruction of 

 the stomata, to which the len- 

 ticels succeed ; B, at end of 

 first season's growth. One and 

 one-half times natural size 



