CHAPTEE III 

 CONIFERALES 



The representative Gymnosperms, at least of the present 

 time, are Conifers. They include about three hundred recog- 

 nized living species, distributed among thirty-four genera, and 

 constitute fully three fourths of the present Gymnosperm flora. 

 They are characteristic of the temperate regions of both north- 

 ern and southern hemispheres, presenting a sharp contrast in 

 this regard to the Cycads. 



I. THE VEGETATIVE ORGANS 



THE STEM 



The most conspicuous morphological feature of the stem is 

 its regular monopodial branching. The terminal bud continues 

 to be more vigorous than the lateral ones, both in the main axis 

 and in the branches, and as a result the characteristic symmetri- 

 cally conical form of the Conifers is developed (Figs. 37-40). 



The branches are distinctly dimorphic, the two forms being 

 characterized as long shoots and spur shoots. In what may be 

 regarded as the more primitive forms of the stem body both 

 kinds of shoots bear foliage leaves ; but in Pinus the main axes 

 bear only scale leaves, while the spur shoots bear the only foli- 

 age leaves ; in Sciadopitys and Phyllocladus the same condi- 

 tion obtains, except that in the former the spur shoot is appar- 

 ently replaced by the peculiar double needle leaf (Fig. 41), 

 and in the latter it is transformed into the phylloclad. 



An interesting fact in connection with these shoots is that 

 in the seedlings a very different behavior of the shoots may be 

 observed. These " juvenile " and itsually very transient forms 

 may be " fixed " by artificial culture, so that the plant assumes 



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