98 



PRACTICAL BOTANY 



some are much larger than others. The large scars mark 

 seasons when the fruit matured, and much smaller ones show 

 that it dropped before it was full grown. 

 Do fruits generally mature on any given 

 fruit spur two years in succession ? l 



88. Structure of leaf buds. Scaly win- 

 ter leaf buds consist, as shown in Figs. 78 



FIG. 82. Twig of cotton- 

 wood with buds in winter 

 condition 



b.sc, bud-scale scars. Two 

 thirds natural size 



J 



FIG. 83. Cottonwood twigs, April 15 



The flower buds (developing into catkins) 



are fully open, but the leaf buds are still 



closed. Reduced 



and 79, of (a) one or more outer layers of scales ; (>) rudimen- 

 tary leaves ; (e) a central axis, at the tip of which is the growing 

 point (Fig. 36), a region of cells capable of rapid sub-division, 

 by means of which the elongation of the shoot is produced. 



1 See Bailey, Lessons with Plants, Part I. The Macmillan Company, 

 New York. 



