26 
North  American  Coniferce. 
( Am.  Jour.  Pharm. 
\     January,  1896. 
threes.  Most  of  the  species  monoecious,  but  a  few  dioecious  ;  the 
fruits,  except  in  the  genus  Cupressus,  requiring  but  one  year  to- 
mature. 
They  are  mostly  trees  of  slow  growth,  many  of  them  natives  of 
Asia  and  Australia. 
Thuya  (Arbor-vitae),  Libocedrus,  Chamaecyparis,  Cupressus  and 
Juniperus,  each  have  their  representatives  in  the  United  States  * 
while  Thuyopsis,  Biota,  Actinostrobus,  Callitris  and  Fitzroya  are 
oriental  genera. 
The  Junipers  differ  from  the  other  members  of  the  group,  in  the 
fact  that  they  are  dioecious,  and  in  the  fact  that  the  fruits  are  fleshy 
and  berry-like  or  drupaceous,  because  the  cone-scales  become 
coalescent  and  succulent  in  the  process  of  ripening. 
SUB-ORDER  II. 
The  Taxace,e. —  The  Yews  and  their  Congeners. — Macrosporan- 
giate  flowers  not  commonly  cones.  The  macrosporophylls  either 
absent  or  rudimentary,  or  at  least  less  developed  than  in  members 
of  sub-order  I ;  the  seed  usually  projecting  beyond  the  macrosporo- 
phyll,  when  the  latter  is  present  and  partly  enclosed  in  a  succulent 
arillus.    The  flowers  are  dioecious,  and  the  leaves  are  evergreen. 
The  great  majority  of  the  group,  which  number,  about  ninety  spe- 
cies, are  Old  World  or  southern  hemisphere  forms.  Taxus  Cana- 
densis, T.  brevifolia  and  Torreya  Californicum  are  the  American 
species. 
Salisburia,  Cephalotaxus,  Microcachrys,  Podocarpus,  Dacrydium^ 
and  Saxegothea  are  other  genera,  mostly  belonging  to  the  Old 
World. 
CHEMICAL  COMPOSITION. 
The  constituents  of  the  plants  in  this  natural  order  have  been 
but  imperfectly  studied.  Volatile  oils,  resins,  tannin  and  coniferin 
are  the  best  known,  and  all  but  the  last  were  known  and 
used  for  their  economic  value  long  before  any  investigation 
was  made  of  their  chemical  properties.  In  the  old  world,  where 
the  oleoresinous  products  have  been  used  from  time  imme- 
morial, comparatively  little  has  been  done  to  establish  their  true 
chemical  composition.  It  is  only  in  recent  years  that  the  terpenes 
have  been  successfully  investigated.  A  large  number  of  less  im- 
portant compounds  have  been  noted  in  the  conifers  of  the  Old 
