CHAPTER FORTY-SEVEN 



GYMNOSPERMS : THE CONIFERS 



The most important of living gymnosperms are the conifers. 

 They comprise about 350 species generally distributed from the 

 subtropics to the polar limits of tree growth. In North America 

 and Eurasia, pine, spruce, fir, hemlock, cypress, larch, juniper, 

 cedar, and sequoia cover the larger part of the forested areas. 

 In the southern hemisphere the araucarians and podocarps also 

 form extensive conifer forests. 



Among the conifers are the largest and oldest of living plants. 

 They have a deep and wide-spreading root system, an efficient 

 water- and food-conductive system, much-branched stems, and a 

 larger leaf display than the Pteridophytes and cycads. Con- 

 sequently they grow far more rapidly, and are less restricted to 

 particular habitats. Many of the conifers are traversed through- 

 out by resin ducts. 



The conifers have scale-covered buds, and are able to with- 

 stand droughts and the low temperatures of winter. With the 

 exception of the larch and bald cypress, the leaves remain on the 

 trees from 3 to 10 years. Because of the strong terminal 

 buds, they usually form a large excurrent trunk with many small 

 horizontal branches, and the trees become conical in form. Some 

 species, however, after attaining their height growth, become 

 ovoid through the lengthening of their upper lateral branches. 



5. Forest Service 



Fig. 315. Long branch of Western larch {Larix occidentalis) , showing lateral dwarf 

 branches with clusters of leaves and mature cones. 



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