FAMILIES OF FLOWERING PLANTS. 9 



in texture, without the ducts (known technically as tracheids) which 

 traverse ordinary v/oods; it is freely permeated, however, by resin 

 canals. The foliage of conifers is usually scale-like or needle shaped, 

 thou'jh sometimes exhibiting broad and expanded blades. The geogra- 

 piiical distril>ution of the trees belonging to this order is (juite exten- 

 sive, although marked peculiarity is shown in individual groups. The 

 largest genera range through the temperate regions of l)oth hemispheies, 

 while many of the smaller genera are restricted to a very limited terri- 

 tory. The reader interested in this phase of the subject will do well 

 to consult Professor Coidter's article in Vol. Ill, No. '2, of The Plant 

 WoKLD, which discusses the distribution of individual groups*. In 



Fi(i. 6.— Spruces boi-dering- a peat bog. Farther back are tamaracks anrt pines. The flowers 

 seen In the bog are those of the snake-mouth orchid (Pogoiiia ophioglosnoides). (Prom MacMil- 

 lans '•Minnesota Plant Lite" by courtesy of the author). 



respect to habitat, coniferous trees usually present well marked areas or 

 zones; thus everyone is familiar with the tamarack swamps of the 

 north, the cypress swamps of the south, and the tracts of pine woods 

 where a single species is the dominant type, in many parts of the 

 country. This is well illustrated in Fig. 6. 



After these general considerations we may proceed to examine the 

 various groups into which the Coniferae are divided. There are two 



