Underground Stems. 13 



or sometimes thickened and gorged with plant food as in the 

 Onion. 



D. Abundance of secondary roots produced, for the most part, 

 upon the lower side. 



E. Buds only imperfectly, if at all, protected by bud-scales. 



Sketch a tuber (^) naming all the parts mentioned. 



ROOTSTOCK OF GINGER ROOT [Asarum Canadense). 



There is a definite annual growth each year. The season's 

 vegetative growth culminates in a pair of long petioled reniform 

 leaves. 



These by their scars indicate the limits of a year's growth. 

 How old is the rootstock in hand ? Note that decay begins when 

 the rootstock is of about a certain age. Is there any difference in 

 the appearance of the rootstock at different ages ? 



How many nodes in a single year's growth ? Note that 

 while the pair of leaves appear to be opposite they are in reality 

 alternate as shown in the older rootstocks. 



What is the arrangement of leaves upon the rootstock ? 



Is a flower borne between the leaves every year? Is it termi- 

 minal or axillarv ? 



From what node are branches most apt to spring? Note 

 that after a certain number of years a branch becomes an inde- 

 pendent plant. In this way a large number of separate plants may 

 be but the parts of a single individual. Compare this with vegeta- 

 tive reproduction in the Jerusalem artichoke and the common 

 potato. 



Sketch the rootstock (|) showing parts mentioned. 



II. ROOTSTOCK OF QUACK GRASS [Agropyrum repens). 



This plant belongs to the Order Gramineae (The grasses). All 

 the plants of this order have their leaves arranged according to 

 the one-half plan. 



There is a single sheathing rudimentary leaf at each node 

 in the axle of which is a small white or pinkish bud. 



Select any bud, and it will be found that the bud at the first 

 node above and the first node below, are upon the oppo.site side of 



