CHAPTER XVIII 

 GYMNOSPERMS 



276. Introduction to spermatophytes. The highest division 

 of the plant kingdom is the seed plants, or spermatophytes. 

 The name means "seed plants." This is the division usually 

 thought of when people speak of plants, since in it are the 

 forms that make up the conspicuous flora of the earth, as well 

 as those that furnish most of our food, timbers, fibers, etc. 

 It is the division with which agriculture, horticulture, garden- 

 ing, and many of the industries are chiefly concerned. It is 

 highly important botanically as well as economically. 



There are two great classes of the division, the gymno- 

 sperms, or naked-seeded spermatophytes, and the angiosperms, 

 or inclosed-seeded spermatophytes. In this chapter we shall 

 discuss the gymnosperms. 



277. The pine. There are over four hundred living species 

 of gymnosperms. Of these the most widely distributed mem- 

 ber is the pine {Pinus, Fig. 246). There are many species of 

 pines, and while but a few kinds are usually found in one 

 locality, the resemblances between all of them are such that 

 one is likely to recognize a pine if once he has carefully noted 

 the characteristics of any species. 



Sometimes pines form dense forests of tall, straight trees. 

 They often stand close together. It is only when they grow 

 thus crowded that they become tall, since when growing alone 

 in open regions they secure ample light without attaining such 

 a height. In German, American, and other forest plantations 

 young pines are planted close together; then when they have 

 reached toward the light and have acquired a medium height, 

 some are removed and used, and their removal gives the remain- 

 ing trees more space in which to spread. Finally, new young 



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