USES OF STEMS. 55 



U.SKS 01 M I.MS. 



1. Dig up a growing plant of ginger, wash 

 it free from soil and notice the underground 

 stem (the ginger of commerce) irregularly lobed 

 and bearing a large number of buds. The 

 younger buds, are still covered over by scale- 

 leaves. The older buds have grown above the 

 soil and formed green leaves ; notice, particular- 

 ly at the base of the leafy stem, the gradual 

 change from scale-leaves to ordinary green 

 leaves. On the old portions of the under- 

 ground stem the scale-leaves will have fallen 

 off but their former positions are indicated by 

 the scars which form characteristic ridges. 

 The thick roots which arise from the lower 

 portion of the stem are, by their form and 

 the absence of scale-leaves, easily distinguished 

 from the stem. 



:2. Examine plants of English potato, yams 

 and eddoes. These all show enlarged under- 

 ground stems of the kind known as tubers. 

 Wash free from earth and notice the 'eyes.' 

 Place some for a few days in a moist place 

 (burying in damp sand answers well) and see 

 how from the ' eyes ' leafy stems arise. 



tf. Examine plants of bean and convolvu- 

 lus, and notice how they climb by twining their 



