﻿252 
  KEY 
  AND 
  FLORA 
  

  

  Heads 
  numerous 
  ; 
  involucre 
  glabrous. 
  Akenes 
  flattened, 
  margined, 
  

   3-nerved 
  on 
  each 
  side, 
  smooth. 
  In 
  waste 
  places.* 
  

  

  XIX. 
  LACTUCA 
  L. 
  

  

  Annual, 
  biennial, 
  or 
  perennial 
  ; 
  stems 
  leafy. 
  Leaves 
  entire 
  

   to 
  pinnately 
  cut. 
  Heads 
  panicled 
  ; 
  involucre 
  cylindrical 
  ; 
  bracts 
  

   unequal, 
  overlapping 
  in 
  2 
  or 
  more 
  rows, 
  the 
  outer 
  shorter 
  ; 
  

   receptacle 
  naked. 
  Flowers 
  blue, 
  yellow, 
  or 
  white 
  ; 
  rays 
  trun- 
  

   cate, 
  5-toothed 
  at 
  the 
  apex. 
  Akenes 
  compressed, 
  ribbed, 
  the 
  

   apex 
  contracted 
  into 
  a 
  slender 
  beak, 
  which 
  is 
  enlarged 
  into 
  a 
  

   disk 
  bearing 
  the 
  soft, 
  hairy, 
  white 
  or 
  tawny 
  pappus.* 
  

  

  1. 
  L. 
  canadensis 
  L. 
  WILD 
  LETTUCE. 
  Biennial; 
  stem 
  erect, 
  

   smooth, 
  hollow, 
  branched 
  above, 
  3-10 
  ft. 
  high. 
  Leaves 
  lanceolate 
  

   to 
  spatulate, 
  pale 
  beneath, 
  the 
  lower 
  petioled 
  and 
  pinnately 
  cut, 
  the 
  

   upper 
  sessile, 
  clasping, 
  and 
  nearly 
  entire. 
  Heads 
  numerous, 
  about 
  

   20-flowered 
  ; 
  flowers 
  yellow. 
  Akenes 
  oval, 
  flat, 
  1-ribbed 
  on 
  each 
  side, 
  

   minutely 
  roughened, 
  about 
  as 
  long 
  as 
  the 
  beak 
  ; 
  pappus 
  white. 
  In 
  

   waste 
  places.* 
  

  

  2. 
  L. 
  acuminata 
  Gray. 
  BLUE 
  LETTUCE. 
  Stem 
  very 
  leafy, 
  smooth, 
  

   paniculately 
  branched 
  above, 
  3-6 
  ft. 
  high. 
  Leaves 
  ovate 
  to 
  lanceo- 
  

   late, 
  taper-pointed, 
  often 
  hairy 
  beneath; 
  the 
  lower 
  on 
  winged 
  petioles 
  

   and 
  often 
  sinuate-lobed, 
  the 
  upper 
  sessile. 
  Heads 
  racemed, 
  on 
  diver- 
  

   gent 
  and 
  bracted 
  peduncles 
  ; 
  flowers 
  blue. 
  Akenes 
  slightly 
  com- 
  

   pressed, 
  beak 
  very 
  short 
  ; 
  pappus 
  white. 
  In 
  waste 
  places.* 
  

  

  XX. 
  AGOSERIS 
  Raf. 
  

  

  Herbs, 
  usually 
  appearing 
  stemless. 
  Basal 
  leaves 
  tufted, 
  

   usually 
  sessile. 
  Head 
  solitary, 
  large, 
  yellow 
  or 
  rarely 
  purple, 
  

   on 
  a 
  naked 
  or 
  bracted 
  scape 
  ; 
  bracts 
  of 
  the 
  involucre 
  overlap- 
  

   ping 
  in 
  2 
  or 
  3 
  rows 
  ; 
  receptacle 
  flat, 
  naked 
  or 
  pitted. 
  Akenes 
  

   smooth, 
  10-ribbed, 
  with 
  or 
  without 
  a 
  beak; 
  pappus 
  of 
  abundant 
  

   slender 
  white 
  bristles. 
  

  

  B. 
  Fl. 
  species 
  1 
  (Nothocalais). 
  

  

  1. 
  A. 
  cuspidata 
  Steud. 
  Scape 
  1 
  ft. 
  or 
  more 
  high. 
  Leaves 
  lanceolate 
  

   taper-pointed, 
  woolly-margined. 
  Involucral 
  scales 
  lanceolate, 
  sharp 
  

   pointed. 
  Akenes 
  beakless. 
  Prairies 
  and 
  plains 
  AV. 
  

  

  2. 
  A. 
  glauca 
  Steud. 
  Scape 
  stout, 
  1-2 
  ft. 
  high. 
  Leaves 
  varying 
  

   from 
  linear 
  to 
  oblong, 
  entire, 
  dentate 
  or 
  pinnately 
  cut. 
  Heads 
  1-2 
  

   in. 
  in 
  diameter. 
  Akenes 
  beaked. 
  Plains 
  W. 
  

  

  