NATURE OF PLANTS 69 



winds which would rob them of water at a time when none could 

 be obtained from the soil. It is quite natural to think of these 

 devices as protection against cold, but strangely there is no adap- 

 tation known among plants that serves primarily as a protection 

 against low temperatures, and there is no cold upon the earth 

 so intense that it may not be endured by many plants, if this 

 were the only unfavorable factor. 



Buds are usually found singly in the axils of the leaves and as 

 a rule only a few that are favorably situated as regards the light 

 ever develop. The development of the buds brings about the 

 characteristic appearance or habit of the plant. This growth is 

 not controlled alone by the favorable position of the buds but 

 also by the interaction or correlation of all the growing parts. 

 As a result in some trees we find a single terminal bud that is 

 larger and better developed than all others. This bud will pro- 

 duce the longest shoots and consequently such trees will have 

 spire-like stems as in the spruces, larches, etc. In other cases 

 this same type of growth may continue for a time but eventually 

 terminal buds of equal vigor will be developed upon several 

 branches and consequently equal growths or diffuse types of 

 branching will result as in the maples, elms, etc. Buds that are 

 not favorably located generally perish after a few years but not 

 infrequently they remain alive and become overgrown by the 

 increase of the stem. In such cases the bud grows slowly and 

 maintains itself near the surface of the wood. These buds grow- 

 ing and often branching in the wood produce those curlings and 

 twistings in the grain that are commonly known as bird's-eye 

 wood. Somewhat similar markings are also produced by minute 



time only develops a leafy shoot reaching to 9. Buds 8 and 9 both produce 

 fruit the next season (o'", a^'^) and short lateral branches reaching to 10 and 1 1 . 

 These buds during the present season only formed leafy shoots. 



Buds are formed in the axils of all the leaves that appear on the shoots of a 

 season's growth, but notice that but few or none at all develop. Some have 

 a thrifty growth, others remain small and perish after one or more years. 

 This is true of the fruit. Some of the pears mature, as is indicated by size 

 of the scars, while others drop off after one or more months. Note also the 

 almost regular alternation in the production of shoots bearing fruit and leaf 

 shoots. Bud 6 is the only exception to this succession. Observe that the 

 branches assume different positions and that the extent of the elongation of 

 the shoot from year to year varies. Can you explain these facts? 



