ro8 



THE VEGETATIVE ORGANS 



occurs at the leaf-base. This is of common occurrence in 

 plants ; and the Yew, Ivy, and Virginia Creeper provide 

 further interesting examples. By means of a pocket lens 

 carefully examine the mode of attachment of the leaf to 

 the stem. The three parts of a typical leaf are easily 

 determined : (i) the swollen base, each 

 side running as a ridge down the stem ; 

 (2) the short stalk marked off from the 

 base by a dark transverse line, and (3) 

 the ovate, entire, acute blade. 



Bend the leaf back and press the 

 bent stalk against the stem until it 

 snaps. Where does the break occur ? 

 Repeat this and notice that the dark 

 line is a line of separation (Fig. 65, s). 

 Examine older shoots for leaf-scars, and 

 notice that when the leaves fall it is the 

 blade and stalk that are thrown off, and 

 that the base remains on the axis as a 

 more or less prominent scar. Compare 

 other shrubs and trees in this respect, 

 e. g. the Common Ash. 



Horse-Chestnut. If a twig of Horse- 

 Chestnut (Fig. 66) be examined we may 

 learn much of its history. At the end is 

 a large terminal bud, and below this are 

 two large leaf-scars each showing seven 

 dots, which are the broken ends of veins, 

 while above each scar is a small bud. 

 Lower down, at intervals, are other crossed pairs of scars and 

 buds, the lowest of the series being frequently smaller than 

 the rest, and below these again we find a number of small 

 scars crowded together. Even these are in crossed pairs, 

 the scars being the scale-scars of last year's terminal bud, 

 and in their axils are tiny buds which, in ordinary circum- 



Fig. 65. Shoot 

 of Privet. l.s, 

 leaf-scar; s, separa- 

 tion-layer. 



