THE BtTD. 



31 



176. NODES. The points at which leaves are pro- 

 duced are called NODES, because the tissues are there 

 condensed into a kind of knot, as you may see by examin- 

 ing any leaf-bearing twig, and also at figs. 10 and 11. 

 The nodes are very distinctly marked when the base of 

 the leaf surrounds, or nearly surrounds, the stem, as in 

 the Polygonum tribe, one of which you may see in this 

 volume under the delineation of Polygonacea3. The 

 nodes are sometimes called joints, and there is occasion- 

 ally a teal articulation at these points ; but if they are 

 marked no otherwise, they are rendered conspicuous by 

 the scars of the falling leaves. 



177. INTERNODES are the spaces between the nodes. 

 The rudimental stem consists of a definite number of 

 these leaf-bearing points and the undeveloped spaces 

 between ; and the growth consists in an elongation of the 

 whole extent, so that the nodes are gradually drawn apart, 

 giving room for a free expansion of their leaves, 



178. The stem, as you have seen, is lengthened by 

 the expansion of the terminal bud (fig. 10). Palms, 

 with few exceptions, produce only terminal buds, when 

 the stem is entirely without branches, and is said to be 

 SIMPLE. But most plants show a disposition to produce 

 branches. These spring from lateral buds, which are 

 termed AXILLARY, because they arise from the axila of 

 leaves, or the angle between the leaf, or leaf-stalk and the 

 stem, as in fig. 11. By this means the undeveloped axes, 

 or growing points, are multiplied, and the tree extends 

 itself horizontally. Every branch may thus be considered 

 a new system of vegetation ; for it multiplies the starting 

 points, and continually repeats the primitive process of 

 development, every particular branch and branchlet being 

 crowned at last by a terminal bud. 



179. ARRANGEMENT OF THE BRANCHES. As these 

 are developed in the axils of the leaves, it is obvious that 

 they must have the same arrangement. Branches are 

 OPPOSITE when they spring from the axils of opposite 

 leaves, as in the Lilac and Horse-Chestnut ; when they 

 spring from the axils of l&ves alternately arranged, 

 they are ALTERNATE, as iff the Chestnut, Lime-tree and 

 Buttonwood ; and when they spring from the axils of 

 leaves occupying a ring round the stem, they are VER- 

 TICILLATE, or whorled. 



180. Were there no interruption of these secondary 

 means of development, the tree would be perfectly sym- 

 metrical ; but several circumstances interfere with them, 

 and more or less impair the symmetry of growth. These 



are chiefly Undeveloped Buds, Adventitious Buds, and 

 Superfluous Buds. 



181. UNDEVELOPED BUDS. The whole number of 

 buds formed by trees are never at any time developed. 

 Indeed they cannot be all of them designed for develop- 

 ment; but in their plentiful production, the means of 

 continuing the plant are multiplied, and provision is 

 made for cases of accident. If the terminal bud is 

 destroyed, some of the lateral buds, which else would 

 have remained inert, are put forth, and thus supply its 

 place. In this way, when the foliage of trees has been 

 destroyed by canker-worms, or frost, they are often re- 

 clothed so rapidly, that their returning verdure seems to 

 have been recalled by the power of magic; but the 

 necromancy rests entirely in the sudden development of 

 latent buds. 



182. Buds which have remained latent, embedded 

 for years in the trunk of trees, when approached by an 

 accidental opening, have forced their passage through the 

 wood, and put forth into new branches. The non-devel- 

 opment sometimes proceeds in a regular order. When 

 the branches are opposite, the growing points are gene- 

 rally crowned by three buds, but all of these seldom 

 grow. The terminal bud usually continues the growth, 

 and the two lateral ones remain latent, as in the Maple. 

 But sometimes the lateral buds are developed, and the 

 terminal one is suppressed, when the stem becomes regu- 

 larly forked, as in the Lilac, and the beautiful little plant 

 known as Innocence, fig. 9. 



183. ADVENTITIOUS BUDS. Stems that are gorged 

 with sap often produce buds out of the regular order, as 

 in the Willow tribe. These are called ADVENTITIOUS 

 BUDS, and in trees they are usually deposited in the 

 wood, at the ends of the Medullary Rays (198), and 

 spring from the new and tender tissue which has lately 

 been deposited. The beautiful shades in the Bird's-eye 

 Maple are said to be owing to the numerous adventitious 

 buds which have become incorporated with its wood. 



184. SUPERFLUOUS BUDS appear to be often produced 

 by an irregular multiplication of the axillary buds. 

 Thus in extremely vigorous trees, three buds may be 

 produced instead of two, or two instead of one. But all 

 these irregular multiplications of the bud have one com- 

 mon origin in the excess of nutriment and of vitality 

 in the vegetable tissues. 



185. Thus the symmetry of a tree may be disturbed 

 by two very important influences first, the non-de- 



Points of leaf insertion. K&me. "Why so called? What sometimes 

 called? When conspicuous? Spaces between nodes. Stem lengthened, 

 how? What trees produce only terminal buds? When only these are 

 produced, what arrangement has the stem? How is it generally? How 



are branches produced? Each branch may be considered what? What 

 arrangement have branches? Why? What causes disturb the symmetry? 

 How are undeveloped buds often useful ? What of latent buds ? Shades in 

 Maple- wood, by what caused ? 



