﻿AUGUST 
  19, 
  1922 
  BRITTON 
  AND 
  ROSE: 
  DEERHORN 
  CACTUS 
  

  

  329 
  

  

  Dr. 
  George 
  Engelmann 
  for 
  Joseph 
  Gregg, 
  a 
  well-known 
  collector 
  of 
  

   plants, 
  but 
  on 
  account 
  of 
  its 
  peculiar 
  habit, 
  flowers, 
  fruit 
  and 
  seeds, 
  

   it 
  was 
  made 
  the 
  type 
  of 
  a 
  new 
  genus, 
  Peniocereus, 
  by 
  Britton 
  and 
  

   Rose 
  in 
  1909.2 
  

  

  Fig. 
  1. 
  Peniocereus 
  greggii. 
  — 
  Upper 
  figure, 
  ^ow^r; 
  lower 
  

  

  figure, 
  fruit. 
  

  

  In 
  1921, 
  through 
  the 
  efforts 
  of 
  Dr. 
  B. 
  W. 
  Evermann, 
  a 
  scientific 
  

   expedition 
  was 
  sent 
  out 
  by 
  the 
  California 
  Academy 
  of 
  Sciences 
  to 
  

   explore 
  the 
  islands 
  in 
  the 
  Gulf 
  of 
  California. 
  While 
  engaged 
  in 
  the 
  

   botanical 
  work 
  of 
  this 
  expedition 
  Mr. 
  Ivan 
  M. 
  Johnston 
  collected 
  a 
  

   second 
  species 
  of 
  this 
  genus 
  which 
  is 
  described 
  as 
  follows: 
  

  

  Peniocereus 
  johnstonii 
  Britton 
  and 
  Rose, 
  sp. 
  nov. 
  

  

  A 
  climbing 
  or 
  clambering 
  plant, 
  up 
  to 
  3 
  meters 
  long, 
  with 
  a 
  very 
  large 
  

   fleshy 
  root, 
  sometimes 
  weighing 
  14 
  pounds 
  ; 
  stems 
  and 
  branches 
  3 
  to 
  5-angled, 
  

   the 
  young 
  growth 
  not 
  pubescent; 
  spines 
  9 
  to 
  12, 
  brown 
  to 
  black, 
  glabrous; 
  

   upper 
  radial 
  spines 
  short, 
  stubby, 
  swollen 
  at 
  base, 
  nearly 
  black, 
  the 
  two 
  

   lower 
  light 
  brown, 
  elongated, 
  bristle-like, 
  reflexed; 
  central 
  spines 
  1 
  to 
  3, 
  

   subulate, 
  4 
  to 
  8 
  mm. 
  long; 
  flower 
  (only 
  an 
  old 
  flower 
  seen) 
  about 
  15 
  cm. 
  

   long; 
  perianth-segments 
  about 
  3 
  cm. 
  long; 
  lower 
  and 
  outer 
  perianth-seg- 
  

   ments 
  bearing 
  tawny 
  hairs 
  and 
  long 
  bristles 
  ; 
  flower- 
  tube 
  slender, 
  with 
  promi- 
  

   nent 
  areoles 
  on 
  knobby 
  projections 
  and 
  bearing 
  tawny 
  wool 
  and 
  bristly 
  

   spines; 
  fruit 
  ovoid 
  to 
  oblong, 
  about 
  6 
  cm. 
  long, 
  bearing 
  prominent 
  clusters 
  

   of 
  black 
  spines, 
  dry 
  (?), 
  many-seeded; 
  seeds 
  oblong, 
  3 
  mm. 
  long 
  or 
  more, 
  black, 
  

   shining; 
  seedling 
  dark 
  purple; 
  cotyledons 
  ven- 
  thick, 
  triangular. 
  

  

  Collected 
  by 
  Ivan 
  M. 
  Johnston 
  on 
  San 
  Josef 
  Island, 
  off 
  the 
  west 
  coast 
  of 
  

   southern 
  Lower 
  California, 
  May 
  28, 
  1921 
  (no. 
  3940, 
  type) 
  and 
  June 
  10, 
  

   1921 
  (no. 
  4085) 
  ; 
  also 
  on 
  the 
  mainland 
  at 
  San 
  Nicholas 
  Bay, 
  Lower 
  California, 
  

   May 
  16, 
  1921 
  (no. 
  3737). 
  

  

  This 
  species 
  was 
  always 
  found 
  growing 
  up 
  through 
  bushes 
  of 
  Olneya. 
  

  

  2 
  Contr. 
  U. 
  S. 
  Nat. 
  Herb. 
  12: 
  423. 
  1909; 
  Britton 
  and 
  Rose, 
  Cactaceae 
  2: 
  112. 
  1920. 
  

  

  