﻿BUCKWHEAT 
  FAMILY 
  71 
  

  

  Calyx 
  mostly 
  5-parted, 
  the 
  divisions 
  petal-like, 
  erect 
  and 
  per- 
  

   sistent. 
  Stamens 
  3-9; 
  styles 
  2-3-parted. 
  Fruit 
  lens-shaped 
  

   or 
  3-angled.* 
  

  

  1. 
  P. 
  aviculare 
  L. 
  KNOTGRASS. 
  Annual 
  or 
  perennial. 
  Stem 
  pros- 
  

   trate 
  or 
  ascending, 
  diffuse, 
  smooth, 
  6-24 
  in. 
  long. 
  Leaves 
  small, 
  

   lanceolate 
  or 
  linear-oblong, 
  obtuse, 
  nearly 
  or 
  quite 
  sessile. 
  Sheaths 
  

   thin 
  and 
  dry, 
  2-3-cleft 
  or 
  cut. 
  Flower 
  clusters 
  axillary, 
  1-5-flowered 
  ; 
  

   flowers 
  inconspicuous, 
  nearly 
  sessile. 
  Calyx 
  greenish-white, 
  5-parted, 
  

   the 
  lobes 
  with 
  white 
  or 
  colored 
  borders. 
  Stamens 
  5-8 
  ; 
  style 
  3-parted. 
  

   Akene 
  3-angled, 
  not 
  shining. 
  A 
  common 
  weed 
  in 
  dooryards 
  and 
  where 
  

   the 
  ground 
  is 
  trampled.* 
  

  

  2. 
  P. 
  lapathifolium 
  L. 
  Annual. 
  Stem 
  branching, 
  1-4 
  ft. 
  high. 
  

   Leaves 
  lanceolate 
  or 
  broader, 
  wedge-shaped 
  at 
  the 
  base 
  and 
  taper- 
  

   ing 
  from 
  near 
  the 
  base 
  to 
  an 
  extremely 
  slender 
  point, 
  ciliate, 
  vary- 
  

   ing 
  greatly 
  in 
  length. 
  Sheaths 
  not 
  ciliate 
  or 
  fringed. 
  Spikes 
  oblong 
  

   to 
  linear, 
  closely 
  flowered, 
  erect 
  or 
  nearly 
  so, 
  |-2 
  in. 
  long. 
  Calyx 
  

   white 
  or 
  pink. 
  Stamens 
  6 
  ; 
  style 
  2-cleft. 
  Akene 
  ovate, 
  lens-shaped, 
  

   j- 
  1 
  ^ 
  in. 
  wide 
  or 
  less. 
  In 
  wet 
  soil. 
  

  

  3. 
  P. 
  acre 
  HBK. 
  WATER 
  SMARTWEED. 
  Perennial. 
  Smooth 
  or 
  

   nearly 
  so 
  ; 
  stems 
  erect 
  or 
  ascending, 
  rooting 
  below, 
  2-5 
  ft. 
  high. 
  

   Leaves 
  lanceolate 
  or 
  broader, 
  tapering 
  at 
  both 
  ends, 
  petioled, 
  ciliate, 
  

   translucent-dotted, 
  acrid, 
  U-8 
  in. 
  long. 
  Sheaths 
  cylindrical, 
  falling 
  

   early, 
  bristly-fringed. 
  Spikes 
  erect 
  or 
  nearly 
  so, 
  loosely 
  flowered, 
  f-3 
  

   in. 
  long. 
  Calyx 
  whitish-greenish 
  or 
  flesh 
  color. 
  Stamens 
  8 
  ; 
  style 
  

   usually 
  3-parted. 
  Akene 
  oblong, 
  lens-shaped, 
  smooth 
  and 
  shining. 
  

   Swamps 
  and 
  wet 
  soil, 
  especially 
  S. 
  

  

  4. 
  P. 
  PersicariaL. 
  LADY'S 
  THUMB. 
  Annual. 
  Smooth 
  or 
  nearly 
  so. 
  

   Stem 
  erect 
  or 
  ascending, 
  6-24 
  in. 
  high. 
  Leaves 
  lanceolate 
  or 
  nar- 
  

   rower, 
  tapering 
  at 
  both 
  ends, 
  usually 
  with 
  a 
  dark 
  triangular 
  or 
  cres- 
  

   cent-shaped 
  spot 
  near 
  the 
  center, 
  very 
  variable 
  in 
  length. 
  Sheaths 
  

   more 
  or 
  less 
  bristle-fringed. 
  Spikes 
  ovoid 
  or 
  oblong, 
  dense, 
  erect, 
  

   peduncled, 
  f-2 
  in. 
  long. 
  Calyx 
  pink 
  or 
  purple. 
  Stamens 
  usually 
  6; 
  

   styles 
  2-3-cleft 
  more 
  than 
  half 
  their 
  length. 
  Akene 
  broadly 
  ovate 
  

   and 
  lens-shaped, 
  often 
  somewhat 
  triangular, 
  smooth 
  and 
  shining. 
  In 
  

   waste 
  ground, 
  often 
  a 
  troublesome 
  weed. 
  Naturalized 
  from 
  Europe. 
  

  

  5. 
  P. 
  hydropiperoides 
  Michx. 
  MILD 
  WATER 
  PEPPER. 
  Perennial. 
  

   Stem 
  smooth, 
  slender, 
  erect, 
  decumbent, 
  or 
  prostrate, 
  1-3 
  ft. 
  long. 
  

   Leaves 
  usually 
  narrowly 
  lanceolate, 
  but 
  variable, 
  acute, 
  ciliate, 
  2-6 
  

   in. 
  long. 
  Sheaths 
  wrinkled, 
  bristle-fringed. 
  Spikes 
  erect, 
  slender, 
  

   often 
  with 
  the 
  flowers 
  scattered, 
  i-2.V 
  in. 
  long. 
  Calyx 
  pale 
  pink, 
  

   greenish 
  or 
  nearly 
  white. 
  Stamens 
  8 
  ; 
  style 
  3-parted 
  more 
  than 
  half 
  

   its 
  length. 
  Akene 
  3-angled, 
  smooth 
  and 
  shining. 
  In 
  swamps 
  and 
  

   wet 
  places, 
  especially 
  S. 
  

  

  