CHAPTER VII. 

 GYMNOSPERMS (GYMNOSPER1VLE) 



WHITE PINE (Pinus Strobus) 



Habitat. The gymnosperms are a group of plants higher 

 in the scale of evolution than the pteridophytes, represented 

 by the ferns, horsetails, and club mosses. A common 

 gymnosperm is the white pine (Pinus Strobus), which grows 

 in dry, rocky or sandy soil. 



Morphology of the Sporophyte. The trunk or stem of the 

 white pine tree is erect and vertical. It frequently grows 

 to a height of over a hundred and fifty feet because of the 

 presence of a terminal bud which adds to its height from 

 year to year. From the trunk grow numerous lateral 

 branches, which in turn branch. From the smallest branches 

 grow the acerose foliage leaves which are long, narrow and 

 pointed. The leaves occur in fascicles or groups of five and 

 each group is surrounded by a number of thin scales. 



Defoliation or shedding of the leaves occurs gradually; 

 therefore, the tree always bears green leaves and is known 

 as an evergreen. The sporophyte bears the reproductive 

 organs. 



Reproduction. -^There are two forms of reproduction, (1) 

 asexual and (2) sexual, distinguishable morphologically, but 

 physiologically reproduction is essentially a single sexual 

 process. 



