﻿56 
  KEY 
  AND 
  FLORA 
  

  

  1. 
  C. 
  caroliniana 
  Walt. 
  HORNBEAM. 
  A 
  small 
  tree 
  with 
  smooth 
  

   and 
  close 
  gray 
  bark; 
  twigs 
  slender. 
  Leaves 
  ovate-oblong, 
  acute 
  or 
  

   taper-pointed, 
  sharply 
  and 
  doubly 
  serrate, 
  the 
  straight 
  veins 
  termi- 
  

   nating 
  in 
  the 
  larger 
  serrations 
  ; 
  downy 
  when 
  young 
  and 
  soon 
  be- 
  

   coming 
  smooth. 
  Staminate 
  catkins 
  1-1 
  j 
  in. 
  long. 
  Pistillate 
  catkins 
  

   long-peduncled, 
  8-12-flowered 
  ; 
  bractlets 
  becoming 
  nearly 
  1 
  in. 
  long, 
  

   cut-toothed, 
  the 
  middle 
  tooth 
  much 
  longer 
  than 
  the 
  others. 
  In 
  rich, 
  

   moist 
  woods. 
  Often 
  known 
  as 
  "blue 
  beech 
  " 
  and 
  "ironwood."* 
  

  

  IV. 
  BETULA 
  L. 
  

  

  Trees 
  with 
  slender, 
  aromatic 
  twigs, 
  and 
  thin, 
  usually 
  straight- 
  

   veined 
  leaves. 
  Staininate 
  catkins 
  drooping, 
  flowers 
  usually 
  3 
  

   in 
  the 
  axil 
  of 
  each 
  bract; 
  stamens 
  4, 
  short; 
  anthers 
  1-celled. 
  

   Pistillate 
  catkins 
  erect, 
  flowers 
  2 
  or 
  3 
  in 
  the 
  axil 
  of 
  each 
  bract; 
  

   ovary 
  sessile, 
  2-celled 
  ; 
  styles 
  2 
  ; 
  bracts 
  3-lobed 
  ; 
  perianth 
  none. 
  

   Nut 
  broadly 
  winged.* 
  

  

  1. 
  B. 
  lenta 
  L. 
  CHKRRY 
  BIRCH. 
  Leaves 
  ovate 
  or 
  oblong-ovate, 
  

   acute, 
  heart-shaped, 
  finely 
  and 
  doubly 
  serrate, 
  silky 
  when 
  young 
  ; 
  

   petioles 
  about 
  i 
  in. 
  long. 
  Staminate 
  catkins 
  clustered, 
  3-4 
  in. 
  long. 
  

   Pistillate 
  catkins 
  sessile, 
  about 
  1 
  in. 
  long 
  ; 
  cylindrical 
  bracts 
  spread- 
  

   ing, 
  acute, 
  smooth. 
  River 
  banks, 
  especially 
  N. 
  A 
  large 
  tree, 
  with 
  

   aromatic 
  twigs. 
  The 
  oil 
  contained 
  in 
  the 
  bark 
  and 
  twigs 
  is 
  distilled 
  

   and 
  used 
  as 
  a 
  substitute 
  for 
  wintergreen.* 
  

  

  2. 
  B. 
  lutea 
  Michx. 
  f. 
  YELLOW 
  BIRCH. 
  A 
  large 
  forest 
  tree, 
  some- 
  

   times 
  60-90 
  ft. 
  high, 
  with 
  yellowish 
  or 
  silver-gray 
  bark, 
  which 
  peels 
  

   off 
  in 
  extremely 
  thin 
  layers. 
  Leaves 
  ovate 
  or 
  nearly 
  so, 
  usually 
  taper- 
  

   pointed, 
  rounded 
  or 
  sometimes 
  almost 
  heart-shaped 
  at 
  the 
  base, 
  

   sharply 
  and 
  finely 
  serrate, 
  somewhat 
  downy 
  on 
  the 
  veins 
  beneath, 
  

   3-5 
  in. 
  long. 
  Staminate 
  catkins 
  3-3 
  in. 
  long; 
  pistillate 
  catkins 
  

   about 
  I 
  in. 
  long. 
  Rich 
  woods 
  N., 
  also 
  southward 
  in 
  the 
  mountains. 
  

  

  3. 
  B. 
  nigra 
  L. 
  RIVER 
  BIRCH, 
  RED 
  BIRCH. 
  A 
  medium-sized 
  tree 
  

   with 
  reddish-brown 
  bark. 
  Leaves 
  rhombic-ovate, 
  acute 
  at 
  the 
  apex, 
  

   acute 
  or 
  obtuse 
  at 
  the 
  base, 
  sharply 
  and 
  doubly 
  serrate, 
  white-downy 
  

   below, 
  becoming 
  smoother 
  with 
  ago. 
  ]>otiolos 
  short. 
  Staminate 
  catkins 
  

   2-3 
  in. 
  long. 
  Pistillate 
  catkins 
  1-1 
  \ 
  in. 
  long, 
  peduncles 
  short, 
  bracts 
  

   nearly 
  equally 
  3-cleft, 
  woolly. 
  River 
  banks, 
  especially 
  S. 
  and 
  W.* 
  

  

  4. 
  B. 
  populifolia 
  Marsh. 
  (iitAY 
  Bntm. 
  A 
  tall 
  shrub 
  or 
  slender, 
  

   straggling 
  tree, 
  15-30 
  ft. 
  high, 
  seldom 
  growing 
  erect, 
  often 
  several 
  

   trunks 
  springing 
  from 
  the 
  ground 
  almost 
  in 
  contact 
  and 
  slanting 
  

   away 
  from 
  each 
  other. 
  Leaves 
  triangular, 
  with 
  a 
  long 
  taper 
  point 
  

   and 
  truncate 
  base, 
  unevenly 
  twice 
  serrate, 
  with 
  rather 
  long, 
  slender 
  

   petioles, 
  which 
  allow 
  the 
  leaves 
  to 
  quiver 
  like 
  those 
  of 
  the 
  aspen. 
  

  

  