﻿Arthur: 
  New 
  species 
  of 
  Uredineae 
  477 
  

  

  is 
  one 
  of 
  the 
  most 
  active 
  and 
  resourceful 
  observers 
  of 
  the 
  Uredi- 
  

   nales 
  among 
  American 
  botanists, 
  and 
  who 
  has 
  explored 
  the 
  Rocky 
  

   Mountain 
  and 
  Pacific 
  roast 
  mst 
  flora 
  wifh 
  nnn?»rnl1p1pd 
  fViornno-h- 
  

  

  ness. 
  

  

  Aecidium 
  arctoum 
  sp. 
  nov. 
  

  

  0. 
  Pycnia 
  epiphyllous 
  and 
  to 
  a 
  less 
  extent 
  hypophyllous 
  among 
  

   the 
  aecia, 
  numerous, 
  rather 
  inconspicuous, 
  small, 
  subepidermal, 
  

   in 
  section 
  globoid, 
  128-160 
  /i 
  in 
  diameter; 
  ostiolar 
  filaments 
  

   prominent, 
  up 
  to 
  80 
  ju 
  long. 
  

  

  1. 
  Aecia 
  hypophyllous, 
  subepidermal, 
  diffused 
  on 
  slightly 
  

   paler 
  spots 
  3-7 
  mm. 
  across, 
  cupulate, 
  very 
  small, 
  0.1-0.2 
  mm. 
  in 
  

   diameter; 
  peridium 
  delicate, 
  erect 
  or 
  somewhat 
  recurved, 
  the 
  

   margin 
  erose 
  or 
  fimbriate; 
  peridial 
  cells 
  rhomboidal, 
  16-19 
  by 
  

   28-32 
  /x, 
  somewhat 
  overlapping, 
  the 
  outer 
  wall 
  1-1.5/i 
  thick, 
  

   smooth, 
  the 
  inner 
  wall 
  3-6 
  /x 
  thick, 
  moderately 
  verrucose; 
  aecio- 
  

   spores 
  globoid, 
  or 
  some 
  of 
  them 
  oblong, 
  21-26 
  by 
  23-29 
  /x; 
  wall 
  

   colorless, 
  thin, 
  1-1.5 
  ju, 
  minutely 
  verrucose. 
  

  

  On 
  Elaeagnus 
  angustifolia 
  L., 
  Kulm, 
  North 
  Dakota, 
  June 
  24, 
  

   1919. 
  J' 
  F, 
  Brenckle 
  1235. 
  

  

  The 
  form 
  described 
  here 
  as 
  a 
  new 
  species 
  was 
  found 
  in 
  con- 
  

   siderable 
  abundance 
  on 
  a 
  hedge 
  of 
  the 
  Eurasian 
  oleaster 
  in 
  the 
  

   town 
  of 
  Kulm. 
  Dr. 
  Brenckle, 
  who 
  submits 
  the 
  material, 
  could 
  

   find 
  no 
  rusted 
  grass 
  or 
  sedge 
  in 
  the 
  vicinity 
  that 
  seemed 
  at 
  all 
  

   likely 
  to 
  serve 
  as 
  the 
  alternate 
  host, 
  although 
  it 
  is 
  undoubtedly 
  a 
  

   heteroecious 
  species. 
  The 
  supposition 
  that 
  the 
  rust 
  could 
  have 
  

   been 
  imported 
  with 
  the 
  hedge 
  plants 
  can 
  be 
  dismissed 
  as 
  highly 
  

   improbable, 
  even 
  aside 
  from 
  the 
  fact 
  that 
  no 
  aecial 
  form 
  on 
  this 
  

   group 
  of 
  hosts 
  is 
  known 
  in 
  the 
  region 
  where 
  the 
  host 
  is 
  native. 
  

  

  The 
  spores 
  are 
  very 
  much 
  smaller 
  than 
  those 
  oi 
  Aecidium 
  Allenii 
  

   Clint., 
  on 
  Elaeagnus 
  argentea 
  from 
  North 
  Dakota, 
  as 
  well 
  as 
  those 
  

   of 
  A. 
  Elaeagni 
  Diet, 
  and 
  A. 
  minoense 
  Sydow 
  from 
  Japan. 
  There 
  

   IS 
  a 
  Japanese 
  form 
  on 
  Elaeagnus 
  glabra 
  with 
  spores 
  of 
  nearly 
  the 
  

   same 
  size, 
  but 
  it 
  has 
  larger 
  and 
  firmer 
  aecia, 
  and 
  other 
  character- 
  

   istics 
  which 
  distinguish 
  it. 
  In 
  spite 
  of 
  the 
  appearance 
  of 
  this 
  

   form 
  on 
  an 
  exotic 
  shrub 
  under 
  conditions 
  of 
  cultivation, 
  it 
  seems 
  

   most 
  likely 
  to 
  be 
  a 
  native 
  rust 
  that 
  has 
  found 
  a 
  congenial 
  host 
  in 
  

   this 
  foreign 
  plant. 
  

  

  Aecidium 
  renatum 
  sp. 
  nov. 
  

   O. 
  Pycnia 
  epiphyllous, 
  inconspicuous, 
  subepidermal. 
  

  

  