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FAMILIES OF FLOWERING PLANTS. 9 
in texture, without the ducts (known technically as tracheids) which 
traverse ordinary woods; it is freely permeated, however, by resin 
canals. The foliage of conifers is usually scale-like or needle-shaped, 
though sometimes exhibiting broad and expanded blades. The geogra- 
phical distribution of the trees belonging to this order is quite exten- 
sive, although marked peculiarity is shown in individual groups. The 
largest genera range through the temperate regions of both hemispheres, 
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 Coulter’s article in Vol. III, No. 2, of Tar Prantr 
Wortb, which discusses the distribution of individual groups. In 
Fic. 6.—Spruces bordering a peat bog. Farther back are_ tumaracks and pines. The flowers 
seen in the bog are those of the snake-mouth orchid (Pogonia ophioglossoides). (From MacMil- 
lan’s ‘“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 
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