UNDER-GROUND BUDS 117 



The bulb of which common examples are those of 

 the so-called garden ' Lilies ' EUCHARis, CRINUM, and 

 PANCRATIUM, is another form of under-ground shoot, 

 but this unlike all the others has a very short axis 

 on which are many thick leaves closely crowded 

 together. It is in fact a bud, the leaves of which 

 .are very thick and large. In some bulbs (e.g. 

 the onion), the outer leaves completely overlap and 

 enclose the inner, and the outermost of all are very 

 thin, like paper, and brown. In others (as in LILIUM) 

 all the scales are alike thick, and the outer are shorter 

 ;so that the surface of the bulb is rough or scaley, not 

 smooth as in the onion. Some of the scales are not 

 -merely reduced leaves, but are the bases of the green 

 leaves which were formed during the proceeding 

 vegetative season, and whose tops have died down 

 and withered away. 



7. Now if we ask what are the reasons for all 

 ihese different kinds of shoots, why some plants climb 

 .and others creep, why some have stolons or bulbs 

 or rhizomes, we shall find the answer by keeping in 

 mind the work that a plant has to do, and the kind 

 of soil and situation in which each grows. 



8. It is in places where the soil is too thin and 

 shallow to allow trees and shrubs to grow, that we 

 find the annual type at its best. On the slopes of 

 hills and in valleys, where the rainfall is good so that 

 there is plenty of moisture and the soil is rich and 

 deep, grow, unless destroyed by man or other animals, 

 the finest specimens of the opposite type tall well 

 branched trees under whose shade there is generally a 

 thick undergrowth of such shrubs and perennial herbs, 



