162 
FIRST BOOK. 
2. Of course the boys had often eaten the 
tubers; but they had taken very Kttle notice of 
the plants when they had seen them growing, for 
no one had ever talked about them as their 
uncle did. 
3. He would say sometimes, '^You will never 
be good planters when you are men, if you do 
not understand the habits of your plants, and 
know what soils suit them best." 
4. Mr. Hill wished the boys to observe how 
unlike each other the plants of yams, cocoes, and 
sweet potatoes are in the parts above ground. 
^^What sort of stems have they?" he asked 
them. 
5. " The yams and sweet potatoes have slender 
stems," replied Fred. 
" Yes, too slender to hold themselves upright," 
added his uncle. So what do they do?" 
6. " The yam twines its stem round a stake or 
anything else that is near it," said Harry. 
7. And the sweet potato stem creeps along 
the ground," his brother added. 
" Very well. Then one is a climbing, and the 
other a trailing stem," said Mr. Hill; ''and as 
the long stem of the potato trails along, it sends 
out roots and tubers at every joint that rests on 
the ground. 
8. " The coco plant, on the other hand, seems 
