356 



PLANT STUDIES 



236. Conifers. — This is the great modern Gymnosperm 

 group, and is characteristic of the temperate regions, where 

 it forms great forests. Some of the forms are widely dis- 

 tributed, as the great genus of pines {Pinus) (Fig. 57), 

 while some are now very much restricted, although for- 

 merly very widely distrib- 

 uted, as the gigantic red- 

 woods (Sequoia) of the 

 Pacific slope. The habit of 

 the body is quite charac- 

 teristic, a central shaft ex- 

 tending continuously to the 

 very top, while the lateral 

 branches spread horizontal- 

 ly, with diminishing length 

 to the top, forming a coni- 

 cal outline (Figs. 56, 57). 

 This habit of firs, pines, 

 etc., gives them an appear- 

 ance very distinct from that 

 of other trees. 



Another peculiar feature 

 is furnished by the char- 

 acteristic " needle-leaves," 

 which seem to be poorly 

 adapted for foliage. These 

 leaves have small spread of 

 surface and very heavy pro- 

 tecting walls, and show adap- 

 tation for enduring hard 

 conditions (Fig. 308). As 

 they have no regular period of falling, the trees are always 

 clothed with them, and have been called " evergreens." 

 There are some notable exceptions to this, however, as in 

 the case of the common larch or tamarack, which sheds its 

 leaves every season (Fig. 56). 



Fig. 317. Arbor-vitae (Thvja), showing a 

 branch with scaly overlapping leaves, 

 and some carpellate cones (strobili).— 

 After EicHLER. 



