11 



THE STEM. 



THE stein or trunk of taxaceous and coniferous trees is the direct 

 prolongation of the axis of the seedling plant, which is itself a 

 development of the axis of the embryo. Usually, under cultivation 

 and perhaps always in a wild state, if the seed germinates in spring, 

 the axis of the seedling continues to lengthen after the development of 

 the cotyledons during the same season ; it then produces foliage 

 leaves that are often very different from those subsequently produced 

 on the older parts of the stems and branches. The termination of 

 the first stage of growth is marked by a scaly winter bud in all 

 the species included in the Fir and Pine tribe (Abietineit), in most 

 of the cultivated Taxads, in Sciadopitys, Taxodium, and Sequoia 

 scmpervirens.* From this bud the axis continues to lengthen in the 

 following season and to produce leaves that gradually take the 

 form characteristic of the species. In the Abietineie, at the 

 termination of the growth of the axis in the second, and still 

 more conspicuously in the succeeding seasons, the apical bud is 

 surrounded by a variable number of smaller buds from which 

 branches are developed in the following year. In the TAXACE^E, the 

 apical bud is usually solitary, but other buds are distributed 

 irregularly over that portion of the stem formed during the current 

 season's growth from which branches are developed in the following 

 year ; it is thence evident how greatly the position and number 

 of both terminal and lateral buds influence the habit of the tree, 

 and how greatly the form and beauty of coniferous trees depend 

 on the branching. Throughout the Cupressinese, in Araucaria and 

 Cunninghamia, and in the Taxodineie, with the exceptions named 

 above, no true winter buds are formed, but during the season of 

 rest, the apex of the shoots is protected by the latest-formed leaves 

 in different stages of development, the older ones usually arching 

 over and enclosing the younger imperfect ones, and which for the 

 time being perform the function of bud scales. 



In all Taxads and Conifers that come under the denomination of 

 trees, the stem or primary axis always grows more rapidly than the 

 branches given off from it, until the upward progress is diminished by 

 age, or arrested by physical causes, the yearly rate of increase being 

 fairly uniform according to age, in each species, but often modified in 

 Great Britain by the varying climatic conditions of the seasons. In 

 this way the stems or trunks continue to ascend year after year; they 

 are for the most part cylindric-conic, gradually tapering from the base 



* In this species the bud formed at the apex of each shoot is intermediate in structure 

 between the true winter buds of the Abietineae and the terminal leafy envelopes of the 

 Capressineee. 



