642 
North  American  Conifer  ce. 
( Am.  Jour.  Pharm. 
L  December,  1896. 
A  CONTRIBUTION  TO  THE  KNOWLEDGE  OF  SOME 
NORTH  AMERICAN  CONIFERS. 
By  Edson  S.  Bastin  and  Henry  Trimble. 
{Continued  from  page  5<5<5.) 
GENERAL  CHARACTERS  OF  THE  GENUS  TSUGA. 
Only  about  seven  species  of  the  genus  Tsuga  are  known,  two,  or 
perhaps  three,  of  these  belong  to  Japan,  two  to  western  North 
America  and  two  to  eastern  North  America.  The  west  American 
species  are  T.  Mertensiana,  Carriere ;  T.  Pattoniana,  Brewer  and 
Watson  ;  and  the  east  American  species  are  T.  Canadensis,  Carriere, 
and  T.  Caroliniana,  Engelmann.  All  of  the  species  are  large  trees 
of  graceful  habit,  and  they  are  closely  allied  to  one  another,  except 
T.  Pattoniana,  which  is  aberrant  in  some  of  its  characters,  approach- 
ing more  closely  in  its  structure  to  the  pines  and  spruces. 
The  hemlocks  are  all  evergreen  trees,  with  slender,  spreading 
branches,  which  are  mostly  horizontal  or  drooping ;  with  flat,  hori- 
zontally spreading,  alternate  leaves,  which,  by  the  direction  they 
take,  appear  two-ranked  or  pectinate ;  they  have  short,  green  peti- 
oles, which  are  inserted  on  slight  elevations  on  the  branches.  The 
staminate  flowers  are  sub-globose  and  axillary ;  the  anthers  are  two- 
celled  and  transversely  dehiscent ;  the  pollen-grains  are  simple.  The 
cones  terminate  the  branchlets  of  the  preceding  year ;  mature  their 
seeds  the  first  year ;  are  pendulous,  ovoid  or  oblong  in  form ;  of 
small  size,  with  thin,  scarcely  woody  scales  that  are  two-seeded,  ob- 
tuse and  persistent.    The  seeds  are  provided  with  wings. 
TSUGA  CANADENSIS,  CARR. 
HEMLOCK. 
DISTRIBUTION  AND  GENERAL  CHARACTERS. 
The  common  hemlock  of  eastern  North  America  is  very  abund- 
ant in  many  localities,  sometimes  to  the  exclusion  of  all  other  trees* 
It  is  also  rather  widely  distributed,  ranging  northward  through 
Nova  Scotia  and  New  Brunswick,  and  through  the  regions  border- 
ing on  the  St.  Lawrence  and  the  Great  Lakes ;  it  occurs  in  all  the 
Eastern  and  Middle  States,  extends  westward  to  the  eastern  border 
of  Minnesota,  and  .  follows  the  Alleghanies  southward  through 
