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  310 
  Harper: 
  A 
  week 
  in 
  eastern 
  Texas 
  

  

  from 
  the 
  coast 
  and 
  about 
  250 
  feet 
  above 
  sea-level. 
  Generally 
  

   speaking, 
  it 
  Is 
  a 
  vast 
  flat 
  plain, 
  diversified 
  in 
  many 
  places 
  by 
  

   mounds 
  about 
  a 
  foot 
  high 
  and 
  a 
  few 
  yards 
  wide 
  and 
  depressions 
  

   or 
  ''hog-wallows" 
  that 
  are 
  even 
  flatter, 
  and 
  less 
  frequently 
  by 
  

   shallow 
  waterways 
  and 
  a 
  few 
  "domes" 
  that 
  are 
  of 
  about 
  the 
  same 
  

   shape 
  as 
  the 
  mounds 
  but 
  many 
  times 
  larger.* 
  

  

  Where 
  the 
  coast 
  prairie 
  extends 
  farthest 
  inland 
  the 
  soil 
  is 
  a 
  

   sort 
  of 
  sandy 
  loam, 
  dry 
  enough 
  in 
  places 
  to 
  afford 
  a 
  suitable 
  

   habitat 
  for 
  a 
  Selaginella 
  of 
  the 
  rupestris 
  group 
  ;t 
  but 
  toward 
  the 
  

   coast, 
  with 
  decreasing 
  altitude, 
  and 
  also 
  with 
  heavier 
  summer 
  rain 
  

   (which 
  naturally 
  counterbalances 
  the 
  evaporation 
  more 
  than 
  the 
  

   same 
  amount 
  in 
  winter 
  would 
  J), 
  the 
  surface 
  becomes 
  more 
  and 
  more 
  

   marshy, 
  and 
  at 
  the 
  same 
  time 
  more 
  clayey, 
  though 
  the 
  reason 
  for 
  

   this 
  is 
  not 
  quite 
  so 
  obvious. 
  In 
  color 
  the 
  soil 
  varies 
  from 
  

   brown 
  and 
  nearly 
  black, 
  and' 
  it 
  must 
  be 
  quite 
  fertile, 
  thaugh 
  the 
  

   tests 
  of 
  evergreen 
  percentages 
  and 
  amount 
  of 
  improved 
  land, 
  which 
  

   have 
  been 
  used 
  for 
  some 
  of 
  the 
  foregoing 
  regions, 
  are 
  hardly 
  

   applicable. 
  

  

  The 
  greater 
  part 
  of 
  the 
  area 
  has 
  never 
  been 
  cultivated 
  (in 
  1910 
  

   only 
  about 
  40 
  per 
  cent 
  of 
  it 
  was 
  in 
  farms 
  and 
  14 
  per 
  cent 
  improved), 
  

   but 
  there 
  is 
  a 
  surprisingly 
  large 
  number 
  of 
  weeds, 
  perhaps 
  attri- 
  

   butable 
  to 
  over-grazing, 
  although 
  very 
  few 
  cattle 
  were 
  in 
  evidence 
  

   at 
  the 
  time 
  of 
  my 
  visit. 
  It 
  is 
  very 
  difficult, 
  for 
  a 
  newcomer 
  at 
  

   least, 
  to 
  tell 
  just 
  which 
  species 
  are 
  weeds 
  and 
  which 
  are 
  natives, 
  

   so 
  that 
  the 
  number 
  of 
  parentheses 
  in 
  the 
  following 
  list 
  should 
  not 
  

   be 
  taken 
  too 
  Hterally. 
  

  

  gray 
  

  

  . 
  * 
  For 
  topographic 
  maps 
  of 
  parts 
  of 
  the 
  coast 
  prairie 
  in 
  Harris 
  County, 
  on 
  a 
  scale 
  

   of 
  two 
  inches 
  to 
  the 
  mile, 
  with 
  one-foot 
  contour 
  intervals, 
  see 
  the 
  Cypress, 
  Addicks 
  

   and 
  Aldine 
  quadrangles 
  of 
  the 
  U. 
  S. 
  Geological 
  Survey, 
  published 
  in 
  1918 
  and 
  1919. 
  

   The 
  narrow 
  wooded 
  areas 
  along 
  streams 
  are 
  indicated 
  by 
  green 
  overprint. 
  

  

  The 
  cause 
  of 
  the 
  prairie 
  mounds 
  is 
  still 
  a 
  mystery 
  (see 
  Plant 
  World 
  17: 
  39, 
  41. 
  

   1914). 
  but 
  the 
  domes 
  are 
  geological 
  structures, 
  which 
  usually 
  indicate 
  accumulations 
  

   of 
  salt 
  or 
  petroleum, 
  or 
  both. 
  The 
  most 
  noted 
  dome 
  in 
  the 
  whole 
  country 
  is 
  Spindle- 
  

   top, 
  a 
  few 
  miles 
  south 
  of 
  Beaumont. 
  Oil 
  derricks 
  are 
  abundant 
  there 
  and 
  in 
  

   numerous 
  other 
  places 
  scattered 
  over 
  the 
  prairie 
  coast. 
  • 
  

  

  t 
  The 
  type 
  specimen 
  of 
  S, 
  Riddellii 
  Van 
  Eseltine 
  (Contr. 
  U. 
  S. 
  Nat. 
  Herb. 
  20: 
  

   162-163. 
  Nov. 
  1918) 
  is 
  from 
  Prairie 
  View. 
  Waller 
  County. 
  

  

  X 
  See 
  Science 
  II. 
  48: 
  208-211, 
  Aug. 
  30, 
  1918, 
  At 
  Port 
  Arthur, 
  in 
  the 
  south- 
  

   eastern 
  corner 
  ot 
  the 
  state, 
  every 
  house 
  has 
  a 
  galvanized 
  iron 
  cistern 
  to 
  catch 
  water 
  

  

  from 
  the 
  roof, 
  indicating 
  copious 
  summer 
  rain 
  and-presumably-unpalatable 
  

   ground-water. 
  

  

  