CHAPTER V. 



BUDS AND LEAF ARRANGEMENT. 



It has already been pointed out that the two parts of the 

 shoot, i.e., stem and leaf, are very closely connected, so that one 

 cannot be defined without reference to the other. Leaves are, in 

 fact, outgrowths from the side of the stem, which generally differ 

 from it in shape, and are developed acropetally (figs. 2, 4, and 

 5 A). Most leaves are flat, and, in a general sort of way, they 

 may be looked upon as modified pieces of stem. Not uncom- 

 monly the sides of a stem are produced into green wing-like 

 expansions. If these, instead of being continuous, were very 

 much developed at some points and reduced at others, something 

 very like leaves would result. Curiously enough, some leaves 

 actually do become continuous at their insertions, with wings on 

 the stem, as in the thistle. 



There is much more to be said about the leaf than was the 

 case either with the root or stem. Their arrangement will first 

 be considered, and then the various kinds of leaf will be dealt 

 with consecutively. 



Leaving the flower out of consideration for the present, imma- 

 ture leaves have a certain arrangement in the bud, which leads 

 up to the arrangement of the mature leaves on the fully-developed 

 stem. 



Buds, as previously mentioned, are young shoots, in which all 

 the parts are very small, and the internodes n on -elongated. The 

 best examples are to be found in trees, which may be instructively 

 studied in early spring. Every branch typically ends in an apical 

 or terminal bud, within which the year's growth is, so to speak, 

 mapped out, nothing but increase in size being needed to produce 

 a leafy shoot (figs. 2, 4, and 5 A). In racemose branching (p. 24) 

 a branch or twig may grow indefinitely in this way, an apical 

 bud being formed every year ready for the next year's growth. 

 A very good instance is the horse-chestnut. An examination of 

 an apical bud of this tree in spring will show a number of firm 

 over-lapping scales on the outside, which are extremely sticky 

 owins: to the secretion of a resinous substance. A longitudinal 



