264 ELEMENTARY SCIENCE 



is that most of them produce flowers. For this reason, 

 Angiosperms are often called "flowering plants." 



That Angiosperms are much more successful plants 

 to-day than Gymnosperms is indicated by the fact that 

 there are only about five hundred kinds of living Gymno- 

 sperms, while there are at least one hundred and forty 

 thousand kinds of living Angiosperms. 



QUESTIONS 



1. State the important things that distinguish the four great 



groups of plants. 



2. What are the differences between Algae and Fungi? 



3. What did plants have to learn in order to be able to live on the 



land? 



4. Which one of the classes of plants has been the most successful ? 



5. What is the difference between the two groups of seed-plants, 



and are both groups useful to us? 



6. Of what use is a flower to a plant? 



