﻿242 
  

  

  INTRODUCTION 
  TO 
  BOTANY 
  

  

  Among 
  the 
  other 
  algye-fungi 
  which 
  cause 
  common 
  destructive 
  

   diseases 
  are 
  those 
  which 
  cause 
  the 
  cranberry 
  gall 
  ; 
  the 
  brown 
  

   rot 
  of 
  lemons 
  and 
  other 
  citrous 
  fruits 
  ; 
  the 
  white, 
  or 
  downy, 
  

   mildew 
  of 
  shepherd' 
  s-purse, 
  the 
  common 
  radish, 
  mustard, 
  and 
  

   turnip 
  ; 
  and 
  the 
  downy 
  mildew 
  of 
  cucumbers, 
  pumpkins, 
  

   watermelons, 
  and 
  lima 
  beans. 
  

  

  230. 
  The 
  sac 
  fungi. 
  Some 
  of 
  the 
  more 
  common 
  sac 
  fungi 
  

   are 
  the 
  cup 
  fungi, 
  the 
  morel, 
  the 
  yeasts, 
  and 
  the 
  mildews 
  ; 
  the 
  

   latter 
  often 
  appear 
  upon 
  leaves 
  of 
  plantain, 
  smartweed, 
  lilac, 
  

  

  FIG. 
  188. 
  Brown 
  rot 
  (Sclerotinia) 
  growing 
  upon 
  old 
  plums 
  

  

  At 
  the 
  right 
  are 
  some 
  of 
  the 
  fruiting 
  cups 
  ; 
  in 
  the 
  middle 
  is 
  a 
  greatly 
  magnified 
  

   portion 
  of 
  the 
  cup, 
  showing 
  the 
  spore-bearing 
  areas; 
  and 
  at 
  the 
  left 
  is 
  one 
  of 
  tho 
  

   spore-bearing 
  threads 
  still 
  more 
  magnified, 
  so 
  as 
  to 
  show 
  the 
  spores. 
  After 
  Duggar 
  

  

  and 
  oak. 
  More 
  fungi 
  belong 
  to 
  this 
  group 
  than 
  to 
  any 
  other, 
  

   and 
  since 
  most 
  of 
  them 
  are 
  parasitic, 
  it 
  is 
  evident 
  that 
  they 
  

   are 
  of 
  great 
  economic 
  importance. 
  They 
  have 
  wide 
  variations 
  

   in 
  form 
  and 
  structure. 
  Usually 
  the 
  parasitic 
  sac 
  fungi 
  grow 
  

   upon 
  instead 
  of 
  within 
  the 
  host 
  plant. 
  From 
  this 
  superficial 
  

   growth 
  haustoria 
  are 
  sent 
  into 
  the 
  tissues 
  of 
  the 
  host 
  plant. 
  

  

  As 
  illustrations 
  of 
  the 
  damage 
  that 
  may 
  be 
  done 
  by 
  mem- 
  

   bers 
  of 
  this 
  group 
  we 
  may 
  cite 
  the 
  brown 
  rot 
  of 
  peaches, 
  

   plums, 
  cherries, 
  and 
  apricots. 
  Old 
  dried 
  fruits 
  are 
  sometimes 
  

   found 
  lying 
  on 
  the 
  ground 
  or 
  still 
  clinging 
  to 
  the 
  trees. 
  These 
  

   "mummies" 
  are 
  a 
  result 
  of 
  the 
  brown 
  rot. 
  Sometimes 
  they 
  

   produce 
  little 
  brownish 
  cups 
  which 
  are 
  the 
  spore-producing 
  

  

  