DICOTYLEDONS 97 



and pods that we have been considering. This group 

 contains all the true flowering plants, and forms the most 

 important part of the vegetation of our globe, numbering 

 not less than one hundred thousand species. It is divided 

 into two great groups, distributed, as we have seen, accord- 

 ing to the number of their cotyledons, into 



129. Monocotyledons and Dicotyledons. — These are 

 further distinguished by the fact that dicotyledons have, 

 as a general thing, net-veined, and monocotyledons, parallel- 

 veined leaves. The cause of this difference, science has 

 never yet been able to explain, so that for the present we 

 shall have to accept it as a fact which we can not under- 

 stand. There are other differences, also, in the structure 

 of the flower and the stem, which will be considered later. 



PRACTICAL QUESTIONS 



1 . Make a list of all the seeds you can think of that have very thick 

 cotyledons. 



2. Draw a liae under all that are used as food by man or beast. 



3. Could a species derive any advantage from tempting animals to 

 eat and destroy its seed? (117.) 



4. What then is the advantage to the plant of providing this food 

 supply? (125.) 



5. Do you find any edible seeds without protection, and if so, 

 account for their want of it. 



6. Make a list of all the albuminous seeds you can think of that are 

 used for food or other jDurposes, such as medicines and unguents. 



7. Do you find as many food materials among these as among the 

 ex-albuminous kind? 



8. Are they in general as well protected as ex-albuminous seeds ? 



9. How do the two compare, in a general way, as to size ? 



10. What part of the following plants do we eat, the fmit or the 

 seed? Corn; wheat; hickory nut; cocoanut; Brazil nut; peanut; 

 beechnut ; string beans ; honey locust ; cofi"ee ; anise ; celery. 



1 1 . From what part of the castor bean do we get the oil ? Of the 

 peanut? Of the cotton seed? 



12. What gives to cotton-seed meal its value as cattle food? 



13. Is there any valid objection to the wholesomeness of peanut oil, 

 and cotton-seed lard ? 



AXDREWS'b BOT. — 7 



