MORPHOLOGY OF STEMS. 45 



So it is in the Butternut (Fig. 89), where the true axillary bud 

 is minute and usually remains latent, while the accessory ones 

 are considerably remote, and the uppermost, which is much the 

 strongest, is far out of the axil : this usually develops, and gives 

 rise to an extra-axillary branch. 



77. Adventitious Buds are such as are abnormal and irregular, 

 being produced without order and from any part of the stem, or 

 even from roots. The latter, like the internodes of a stem, 

 although normally destitute of buds, do produce them notwith- 

 standing in certain cases, especially when wounded, and in some 

 plants (such as Blackberries) so freely that gardeners propagate 

 them by root- cuttings. The stems share this tendency ; and 

 buds are apt to break out on the sides of trunks, especially when 

 wounded or pollarded, or to spring from new tissues produced 

 on cut surfaces, especially where the bark and wood join. Even 

 leaves ma} 7 develop adventitious buds, and then be used for 

 propagation. In Bryophyllum, such buds, followed by rootlets, 

 are freely produced on the margins of the blade or of its leaflets. 

 In Begonia, a leaf, used as a cutting, will root from the base of 

 the petiole stuck in the soil, and produce buds on the blade, at 

 the junction with the petiole, or elsewhere. 



SECTION III. OF THE STEM. 

 1. GENERAL CHARACTERISTICS AND GROWTH. 



78. The Stem is the ascending axis, or that portion of the 

 trunk which in the embryo grows in an opposite direction from 

 the root, seeking the light, and exposing itself as much as pos- 

 sible to the air. All phsenogamous plants possess stems. 1 In 

 those which, in botanical descriptions, are said to be acaulescent, 

 or stemless, it is either very short, or concealed beneath the 

 ground. Although the stem always takes an ascending direction 

 at the commencement of its growth, it does not uniformly retain 

 it ; but sometimes trails along the surface of the ground, or 

 burrows beneath it, sending up branches, flower-stalks, or leaves 

 into the air. The common idea, that all the subterra'nean portion 

 of a plant belongs to the root, is incorrect. Equally incorrect is 

 the common expression that plants spring from the root. Roots 

 spring from the stem, not the stem from the root. (21, 24, 37, 44.) 



1 There are, however, reduced forms in which there is no distinction of 

 axis and foliage ; but most of these are clearly leafless rather than stemless, 

 and not even in Lemna and Wolffia can the stem be said to be wanting. 



