no THE VEGETATIVE ORGANS 



upwards, their tips, for a time, being fastened together by 

 hairs, which soon fall off as the leaf grows. One by one 

 the leaves move outwards ; the leaflets expand and, growing 

 more on the upper than the under side, bend backwards 

 until only the upper surfaces can be seen. Growth on the 

 under side now quickens, and the reverse process occurs, 

 the leaflets being raised until they reach a horizontal 

 position. 



When all have unfolded, examine the shoot from above 

 and notice that they form a closely-fitting pattern, or 

 mosaic. The leaf -blades are mostly at the same level, 

 though they arise at different heights on the stem. The 

 lowest leaves have the longest stalks and the largest blades ; 

 the highest leaves have the shortest stalks and the smallest 

 blades ; those between being intermediate in these respects. 



Meanwhile the scales fall off, the lowest first, leaving 

 narrow, light-brown scars which darken with age. We can 

 thus watch, day by day, the formation of ring- or scale- 

 scars which indicate the beginning of a year's shoot. The 

 uppermost scales have larger bases, are thinner, and turn 

 green, and often remain for some time on the branch after 

 the rest have fallen off. Then they frequently develop 

 little blades (Fig. 69, s), which are different from the lower 

 ones and are in some respects intermediate between them 

 and the foliage-leaves. The fact that they may bear blades 

 suggests that the true scales are really leaf -bases, the blades 

 being usually suppressed. When the intermediate scales 

 do fall off they leave larger and lighter scars than the 

 others. The broken ends of their veins are well seen, and 

 it is easy to detect their scars, even on old twigs. 



Usually seven leaflets are formed, which arise from the 

 top of the leaf-stalk, but often there are only five, and 

 occasionally six occur, in which case the leaflets are not 

 arranged three on each side, but there is a median one with 

 two on one side and three on the other. When the veins 



