33Q 
North  American  Conifer  (E. 
A.m.  Jour.  Pharnu 
June,  1896.  ±  J 
and  the  xylem  were  similar  in  structure  and  in  the  distribution  of  the 
tannin  and  oleoresin  to  the  corresponding  parts  of  other  members 
of  the  Pinaster  group  already  described. 
PINUS  VIRGINIANA,  MILLER. 
PINUS  INOPS,  AITON. 
GENERAL  CHARACTERS. 
This  species  is  commonly  known  as  the  Scrub  Pine  or  Jersey 
Pine.  It  is  a  low,  straggling  tree,  from  15  to  40  feet  high,  the  trunk 
seldom  more  than  a  foot  in  diameter,  rough  and  dark-colored,  top 
rounded  or  flattish,  branches  tortuous,  spreading,  young  shoots 
purplish  and  glaucous,  and  branchlets  frequently  drooping.  The 
cones  are  drooping,  oblong-conical,  sometimes  curved,  2  or  3  inches 
long,  persistent  for  several  years,  the  thickened  scales  tipped  with 
a  straight  or  recurved  awl-shaped  prickle.  Its  leaves  are  rather 
stout  and  rigid,  in  twos,  from  short  sheaths,  1  y2  to  2^  inches  long, 
usually  somewhat  twisted,  with  about  ten  rows  of  stomata  on  the  flat 
side,  and  about  twelve  on  the  convex  side ;  epidermis  of  small  thick- 
walled  cells,  hypoderma  about  three-layered  and  also  rather  small - 
celled,  the  outer  layer  composed  of  thin-walled  cells,  the  other  two 
of  thick-walled  cells  ;  the  secretion  reservoirs  located  in  the  meso- 
phyll  about  midway  between  the  hypoderma  and  the  endodermis, 
and  one  opposite  each  angle  of  the  leaf,  sometimes  also  one  opposite 
the  middle  of  each  face  ;  the  endodermis  large-celled,  with  the  walls 
of  its  cells  but  slightly  thickened  ;  the  two  diverging  vascular  bun- 
dles about  five-rayed.  There  are  few  or  no  lignified  cells  interior 
to  the  endodermis,  except  those  which  belong  to  the  xylem  of  the 
bundles. 
MICROSCOPICAL  STRUCTURE. 
A  cross-section  of  a  stem  of  two  years'  growth  showed  the  fol- 
lowing structure  :  At  the  exterior  an  epidermis  composed  of  rather 
small,  thick-walled,  lignified  and  cutinized  cells  was  still  present  in 
places ;  underlying  this  were  two  or  three  layers  of  thin-walled  par- 
enchyma cells ;  this  was  succeeded  by  one  or  two  layers  of  stone-cells, 
probably  representing  the  outer  layers  of  the  periderm  ;  the  rather 
thick,  cortical  parenchyma  was  destitute  of  lignified  elements,  and 
contained  very  numerous  tannin  cells  irregularly  distributed  among 
ordinary  parenchyma  cells,  which  contained  little  or  none ;  in  this 
region  were  also  scattered  secretion  reservoirs  of  large  size,  similar 
