124 BOTANY PART i 



to come from the flanks and the roots from the lower surface of the main stem. 

 In such a plant, when lateral branches grow up at right angles to the soil, they 

 behave as regards their further branching like erect plants. 



2. THE ORDER OF SEQUENCE OF SHOOTS. If the vegetative cone of the primary 

 axis of a plant, after reaching maturity, is capable of reproduction, a plant with 

 but one axis will result, and the plant is designated UNIAXIAL or HAPLOCAULES- 

 CENT. Usually, however, it is not until a plant has acquired axes of a second 

 or third order, when it is said to be DIPLOCAULESCENT or TRIPLOCAULESCENT, or 

 of the ?tth order, that the capacity for reproduction' is attained. A good illustra- 

 tion of a plant with a single axis is afforded by the Poppy, in which the first 

 shoot produced from the embryo terminates in a flower. As an example of 

 a triplocaulescent plant may be cited the common Plantain (Plantago major], 

 whose primary axis produces only foliage and scale leaves ; while the secondary 

 axes give rise solely to bracteal leaves, from the axils of which finally spring 

 the axes of the third order, which terminate in the flowers. In the case of 

 trees, only shoots of the nth order can produce flowers. Thus a division of 

 labour commonly occurs in a branched plant, which finds its expression in 

 differences of form between the successive shoots. These differ in appearance 

 according to the special function performed by them, whether nutrition, storage, 

 or reproduction. In addition to the essential members in the succession of shoots 

 developed in a determined order, there are non-essential members which repeat 

 forms of shoot already present. These may appear simultaneously with the 

 essential shoots, and serve to increase the size of the plant, as in many annuals ; in 

 many perennial plants they arise as yearly innovations on the stock. 



3. THE DISTRIBUTION OF UNFOLDING BUDS. Only in relatively 

 few cases, as, for example, in herbs, do all the lateral buds of a main 

 axis proceed to grow on as shoots. As a rule many more lateral buds 

 are formed than ever unfold. The remainder become DORMANT BUDS 

 or perish. It would be a needless or even injurious expenditure of 

 material on the part of the plant were all the buds to expand, since 

 the branches would overshadow one another and some would perish. 



Almost all trees possess, especially in the lower region of each annual growth, 

 such dormant buds, which remain for a longer or shorter period capable of further 

 development and can unfold under special conditions. The dormant buds of the 

 Oak, Beech, etc., may be a hundred years old. The shoots that arise on old stems 

 often come from these buds and are thus not adventitious. 



The unfolding of lateral buds may proceed acrope tally or basi- 

 petally, or exhibit no definite order. On highly -branched shoot- 

 systems the more peripheral buds are favoured since they have the 

 best opportunity of favourable exposure of the leaves to the light. 



Nearly all our native trees form only resting buds through the summer while 

 the main shoots are elongating. Later, usually at the commencement of a new 

 period of growth, some of the uppermost buds formed in the preceding season 

 grow into lateral branches. These branches may form a whorl or an apparent 

 whorl (Araucaria, Pinus) ; more commonly the highest buds form long shoots 

 while those below them become short shoots (Pear, Apple). In other shoots, 

 especially those that grow erect, every second, third, or fourth, etc., bud unfolds 



