PLANT FOOD 137 



3. What other advantages, if any, does each of the plants named 

 gain from its earth-seeking (geophilous) habit? 



4. What makes the nut grass so troublesome to farmers ? 



5. Is its nut a root, or a tuber? How can you tell? (190, 191). 



6. Suggest some ways for destroying weeds that are propagated in 

 this way. 



7. Could you get rid of wild onions in a pasture by mowing them 

 down? By digging them up? (193.) 



8. Is it wise for farmers to neglect the appearance of such a weed 

 in their neighborhood, even though it does not infest their own land ? 



9. Name any plants of your neighborhood, either wild or cultivated, 

 that are valued for their rhizomas ; for their tubers. 



10. What part of the plants named below do we use for food or 

 other purposes? Ginger, angelica, ginseng, cassava, arrowroot, garlic, 

 onion, sweet flag, iris, sweet potato, Cuba yam, artichoke. 



1 1 . Why are the true roots of bulbous and rhizome bearing plants 

 generally so much smaller in proportion to the other parts than those of 

 ordinary plants? (192.195.) 



12. If the Canada thistle grows in your vicinity, examine the roots 

 and see if there is anything about them that will help to account for its 

 hardihood and persistency. 



13. If you live in the region of the horse nettle (Solanum caroli- 

 nense), explain how it is enabled to flourish in such hard and forbidding 

 places. 



PLANT FOOD 



MATERIAL. An ounce or two each of different kinds of seeds, and a 

 lamp stove or other convenient means of drying them. A pair of scales. 



196. Solids, Liquids, and Gases. The habit of storing 

 up food in some part of their structure for future use is 

 practically universal among plants. Let us now inquire 

 what this food consists of and where it comes from. 



Take a quantity of seeds of different kinds (about thirty 

 grams of each, or one ounce approximately, will answer), 

 weigh each kind separately and then dry them at a high 

 temperature, but not high enough to scorch or burn them. 

 After they have become perfectly dry, weigh them again. 

 What proportion of the different seeds was water, as indi- 

 cated by their loss of weight in drying? 



Burn all the solid part that remains, and then weigh the 

 ash. What proportion of each kind of seed was of incom- 



