ITS STRUCTURE AND GROWTH. 



93 



159. Buds. The apex of the stem, accordingly, is always crowned 

 with an undeveloped portion, with rudimentary parts similar to 

 those already unfolded, that is, with a Bud. The embryo itself 

 may be viewed as an internode (the radicle) bearing the fundamental 

 bud (the plumule) on its apex, from wliich the whole plant is de- 

 veloped, just as an ordinary bud of a tree or shrub develops to 

 form the growth of the season. Except that, in the latter case, the 

 different steps follow each other more closely ; for the bud usually 

 h?is a considerable number of parts ready formed in miniature before 

 it begins to grow, and has a full store of assimilated sap accumulated 

 in the parent stem to feed upon. This is no less the case in many 

 strong embryos highly developed in the seed, and supplied with 

 abundant nourishment, either in 

 the cotyledons, as in the Pea 

 (Fig. 119) and Oak (Fig. 120), 

 or in the albumen, as in Indian 

 Corn (Fig. 126-130). The 

 strong buds which in many 

 shrubs and trees crown the 

 apex of a stem when it has 

 completed its growth for the 

 season, often exhibit the whole 

 plan and amount of the next 

 year's growth ; the nodes, and 

 even the leaves they bear, being 

 already formed, and only re- 

 quiring the elongation of the 

 intemodes for their fuU ex- 

 pansion. This is rudely shown 

 in the annexed diagrams. Fig. 

 151, 152. As the bud (Fig. 

 153) is well supplied with 

 nourishment in spring by the 

 stem on which it rests, its axis elongates rapidly ; and although the 

 growth commences with the lowest internode, yet the second, third. 



riG. 151. Diagram of the vertical section of a strong bud, sucli as that of Ilorsechestnut. 



FIG. 152. The axis of the same developing, the elongation beginning with the lowest inter- 

 node, soon followed by the others in succession. 



FIG. 153. A year's growth of Ilorsechestnut, crowned with a terminal bud : a, scars left 

 by the bud-scales of the previous year : 6, scars left by the fallen leafstalks : c, axillary buds. 



FIG. 154. Branch and buds (all axillary) of the lilac. 



