MORPHOLOGY 



21 



the bud is brought about. The region of strongest growth in a 

 shoot is always at some distance from its growing point. 



The growth in length and consequent elongation of the shoot is in 

 some cases so slight that the leaves remain close together, and leave 

 no free spaces on the stem, thus forming so called dwarf shoots. As 

 examples of such dwarf shoots may be mentioned the thickly-clustered 

 needles or fascicled leaves of the Larch, the rosettes formed by the 

 fleshy leaves of the House-leek (Sempervivum), and also the flowers of 

 Phanerogams with their thickly-crowded floral leaves. In the ordinary 

 or elongated SHOOTS, such as are formed in the spring by most 

 deciduous trees, the portions of the stem between the insertions of the 

 leaves become elongated by the stretching of the shoot. The stem 

 of a shoot, as contrasted with the leaves, is often spoken of as the 

 axis ; while the portions of the stem axis between the insertions of the 

 leaves are termed the internodes, and the parts of the axis from which 

 the leaves arise the NODES. When the base of the leaves encircles the 

 stem, or when several leaves take their origin at the same node, the 

 nodes become strongly marked (Labiatae). 



In some cases the growth in length of a shoot continues for a 

 longer time at certain intermediate points by means of intercalary 

 growth. Such points of intercalary growth are generally situated at 

 the base of the internodes, as in the case of the Grasses. A displace- 

 ment from the position originally occupied by the members of a shoot 

 frequently results from intercalary growth. A bud may thus, for 

 example, become pushed out of the axil of its subtending leaf, and 

 so apparently have its origin much higher on 

 the stem ; or a subtending leaf, in the course of 

 its growth, may carry its axillary bud along 

 with it, so that the shoot which afterwards 

 develops seems to spring directly from its sub- 

 tending leaf; or, finally, the subtending leaf 

 may become attached to its axillary shoot, and 

 growing out with it, may thus appear to spring 

 from it (Fig. 20). 



Resting Buds. — As a means of protection, 

 buds may become invested, in winter, with 

 scale -like leaves or BUD -SCALES, which are 

 rendered still more effective as protective struc- 

 tures by hairy outgrowths and excretions of 

 resin and gum, and also by the occurrence of 

 air-spaces. Not infrequently the subtending 

 leaf takes part in the protection of its axillary 

 bud, and the base of the leaf-stalk, after the 

 leaf itself has fallen, remains on the shoot and 

 forms a cap-like covering for the winter bud. The buds of tropical 

 plants, which have to withstand a dry period, are similarly protected ; 



Fig. 20. — Samolus Valcrandi, 

 each axillary shoot (a) 

 hearing its subtending 

 leaf (t), and terminating in 

 a flower. (Nat. size.) 



