148 Plant Biology 



The class Angiospermae may be divided into the subclasses ( 1 ) Dicoty- 

 ledoneae (di kot i le -do' ne e) (Gr. di, two; kotyledon, embryonic, seed 

 leaf) and (2) Monocotyledoneae (mon o kot i le -do' ne e) (Gr. mono, 

 one; kotyledon, embryonic, seed leaf). A cotyledon (seed leaf) is a food- 

 storing and food-digesting part of the embryo which supplies it with food 

 during its early development. 



QUESTIONS AND TOPICS 



1. Learn the meaning, correct pronunciation, and derivation of each term used 

 in this chapter. 



2. Define (1) plant kingdom, (2) subkingdom, (3) phylum, (4) subphylum, 

 (5) class, (6) subclass, (7) genus, and (8) species. 



3. Why are Greek and Latin used in composing a system of classification and in 

 forming a scientific name? Of what does a scientific name consist? Give 

 several examples. 



4. Discuss the needs for a scientific classification of plants. List some serious 

 objections to the use of common names in scientific work. 



5. Tell how so many common names may originate for one and the same plant. 



6. Explain what is meant by the binomial system of nomenclature. 



7. Give the general characteristics of each plant phylum. What do certain 

 phyla have in common? Do certain phyla seem to be more closely related 

 to each other than others? Give specific reasons why. 



8. List the total number of species for the plant kingdom. List the number of 

 species in each phylum. How does the total for the plant kingdom compare 

 with the animal kingdom? 



9. Give specific evidence that the representatives of the various phyla increase 

 in complexity of structure and function, as we observe them, from the lower 

 to the higher phyla. What conclusions do you draw from this? 



10. Define a life cycle (life history). Do all plants have a life cycle? 



11. In general, are plants sessile (attached) or motile? List the affects of at- 

 tachment on such phenomena as securing foods, development of the organism, 

 protection, reproduction, etc. 



12. Which plant phylum do you consider to be most important? Give specific 

 reasons why you say so. What makes a plant economically important? 



13. Are all economically important plants necessarily of value? List several 

 plants to prove your point. 



14. Discuss alternation of generations in plants, including how this phenomenon 

 differs from ordinary life cycles. What proportion of plants studied possess 

 alternation of generations? List advantages and disadvantages of this phe- 

 nomenon. 



15. How do plants illustrate the principle of "struggle for existence"? 



16. List a number of ways in which man is influenced (beneficially and detri- 

 mentally) by plants. 



17. Explain the role of plants in a so-called "balanced environment," or "bal- 

 anced community." Can any living organism live entirely by itself in a state 

 of complete isolation? 



