10. THE SHOOT. 23 



The form of the shoot depends largely upon the amount of 

 elongation which the internodes of the stem undergo. Thus, there 

 is in some plants (e.g. the Larch, Pine, and Taxodium, among the 

 Coniferae ; and many Angiosperms) a well-marked distinction of 

 two forms of vegetative shoots. These are the. ordinary elongated 

 branched shoots ; and short shoots, termed dwarf -shoots, which 

 elongate but little, branch scarcely at all, and are frequently of but 

 short duration (see p. 9). Again, in some plants (e.g. most Ferns 

 and Conifers) the primary shoot continues to grow throughout the 

 life of the plant ; whilst in others, the growth of the primary 

 shoot is limited, the further development of the shoot being 

 effected by a lateral branch, itself of limited growth ; so that, by 

 the repetition of this process a cymose branch-system is produced 

 (see p. 21). This mode of development by innovation occurs in 

 many so-called uniaxial plants whose primary shoot terminates in 

 a flower ; and in the seedlings of the Lime, and of the Elm, which 

 form no terminal bud at the close of the first year, the further 

 development of the shoot being effected by the highest lateral bud. 



In plants which live for more than one year, the shoot may 

 either persist from year to year, or it may die down to the surface 

 of the soil in each year, the subterranean parts being alone per- 

 sistent. Shoots which last only one year are termed annual. 



In those shoots of trees which are produced in one season's growth, the 

 lowest internodes, especially those lying between the bud-scales, are very 

 short ; so that it is easy, by noticing the closely-arranged scars of the bud- 

 scales, to determine, in a shoot several years old, the amount of growth 

 during each year. The terminal and the lateral buds of such an annual 

 shoot usually remain in the bud-condition during the first year until the 

 beginning of the next period of growth, so that the age of such a branch- 

 system can be determined by the extent of the branching, the number of 

 years corresponding to the number of times that branching has taken 

 place. In some trees, however (e.g. the Oak), a second shoot, which had 

 hitherto existed in the bud-condition, is regularly developed in the middle 

 of summer. As a general rule, it is only the more anterior (near the apex) 

 of the lateral buds on the shoot which develope in the subsequent year 

 into branches, as is very clearly seen in the whorled branches of the 

 Coniferse ; when, however, the more posterior lateral buds do develope, the 

 branches produced are successively the shorter the further they are from 

 the apex (e.g. Elm). Whilst in many trees (Coniferae, Oak) the ter- 

 minal bud of a shoot always grows into a new shoot in the next year, in 

 others (Lime, Elm, sometimes Beech) this is not the case, but the elongation 

 of the shoot is effected in a sympodial manner by means of the highest 

 lateral bud (see p. 21). 



In the Larch, the dwarf-shoots bear the fascicled leaves, and spring 



