332 NATURE STUDY AND AGRICULTURE 



There are seed-producing plants whose ovules are not 

 enclosed by pistils; so that in them the pollen grains come 

 directly in contact with the ovules, and there is much less 

 extensive development of pollen tubes. These plants are 

 the pines, spruces, etc., known commonly as "evergreens," 

 and scientifically as gymnosperms, which name means 

 "naked seeds." The other and far larger group of seed 

 plants is called angiosperms, which name means " enclosed 

 seeds." 



There are also very many plants that do not produce 

 seeds at all in connection with their reproduction. The vis- 

 ble reproductive bodies are the so-called " spores." These 

 seedless plants, therefore, are sometimes called "spore 

 plants"; but this is unfortunate, because seed plants are 

 also spore-producing plants. The difference in the two 

 cases is not that one group produces seeds and the other 

 produces spores; but that although both groups produce 

 spores, in one of them the work of the spores results in 

 seed formation. 



