﻿APR. 
  19, 
  1922 
  BLAKE 
  : 
  ACANTHOSPERMUM 
  FROM 
  GALAPAGOS 
  ISLANDS 
  203 
  ' 
  

  

  as 
  well 
  developed 
  in 
  such 
  fruits 
  as 
  in 
  normal 
  ones. 
  One 
  is 
  tempted 
  to 
  

   explain 
  the 
  variability 
  of 
  these 
  three 
  forms 
  of 
  Acanthospermum 
  by 
  

   the 
  supposition 
  of 
  a 
  very 
  recent 
  origin. 
  The 
  suggestion 
  may 
  also 
  be 
  

   made 
  that 
  the 
  absence 
  in 
  the 
  Archipelago 
  of 
  native 
  mammals 
  whose 
  

   fur 
  would 
  provide 
  a 
  means 
  of 
  transport 
  for 
  the 
  spiny 
  fruits 
  may 
  be 
  in 
  

   some 
  way 
  correlated 
  with 
  the 
  tendency 
  to 
  loss 
  of 
  spines. 
  This 
  tendency 
  

   toward 
  abortion 
  of 
  spines 
  in 
  the 
  fruits 
  of 
  various 
  unrelated 
  genera 
  of 
  

   plants 
  of 
  the 
  Galapagos 
  Islands 
  has 
  already 
  been 
  mentioned 
  by 
  Robin- 
  

   son,^ 
  and 
  considered 
  explicable 
  by 
  the 
  paucity 
  of 
  indigenous 
  mammals. 
  

   The 
  three 
  species 
  of 
  the 
  Section 
  Lecocarpopsis 
  may 
  be 
  separated 
  by 
  

  

  the 
  following 
  key. 
  

  

  Leaves 
  usually 
  divided 
  about 
  half 
  way 
  to 
  midrib, 
  the 
  rachis 
  4 
  to 
  20 
  mm. 
  wide; 
  

  

  body 
  of 
  fruit 
  4 
  to 
  5 
  mm. 
  deep; 
  horns 
  usually 
  subequal, 
  or 
  the 
  outer 
  longer 
  

  

  or 
  rarely 
  obsolete. 
  

  

  Leaf 
  blades 
  4.5 
  to 
  9 
  cm. 
  long, 
  2.2 
  to 
  4.-5 
  cm. 
  wide; 
  peduncles 
  2.3 
  to 
  4.5 
  cm. 
  

  

  long; 
  horns 
  of 
  fruit 
  3 
  to 
  7 
  mm. 
  long, 
  usually 
  subequal; 
  Hood 
  Island. 
  

  

  A. 
  lecocarpoides. 
  

   Leaf 
  blades 
  1.5 
  to 
  2.5 
  cm. 
  long, 
  1.7 
  to 
  2 
  cm. 
  wide; 
  peduncles 
  about 
  1 
  cm. 
  

   long; 
  horns 
  of 
  fruit 
  1 
  to 
  3 
  mm. 
  long, 
  the 
  outermost 
  the 
  longest 
  ; 
  Gardner- 
  

   near-Hood 
  Island. 
  A. 
  hrachyceratum. 
  

  

  Leaves 
  divided 
  nearly 
  to 
  the 
  midrib, 
  the 
  rachis 
  only 
  1 
  to 
  2 
  mm. 
  wide; 
  body 
  

   of 
  fruit 
  2.2 
  to 
  3.5 
  mm. 
  deep 
  ; 
  inner 
  horns 
  of 
  fruit 
  usually 
  much 
  longer 
  than 
  

   the 
  outer; 
  Chatham 
  Island. 
  A. 
  leptolobum. 
  

  

  Acanthospermum 
  hrachyceratum 
  Blake, 
  sp. 
  nov. 
  Figure 
  1, 
  b, 
  k-m. 
  

  

  Base 
  not 
  seen; 
  stem 
  indurated, 
  60 
  cm. 
  high, 
  dichotomous, 
  densely 
  spreading- 
  

   hispidulous; 
  leaves 
  opposite, 
  hispidulous 
  and 
  gland-dotted 
  above 
  and 
  chiefly 
  

   on 
  the 
  nerves 
  beneath; 
  petioles 
  8 
  to 
  12 
  mm. 
  long, 
  connate 
  at 
  base, 
  narrowly 
  

   margined; 
  blades 
  oval-ovate, 
  1.5 
  to,2.5 
  cm. 
  long, 
  1.7 
  to 
  2 
  cm. 
  wide, 
  obtuse, 
  

   cuneate 
  at 
  base, 
  lobed 
  about 
  to 
  middle, 
  the 
  lobes 
  5 
  to 
  7 
  pairs, 
  cuneate 
  or 
  oblong, 
  

   revolute-margined, 
  and 
  toward 
  apex 
  2 
  to 
  5-lobed 
  with 
  short 
  obtuse 
  densely 
  

   hispidulous 
  lobes; 
  peduncles 
  solitary, 
  terminal, 
  densely 
  sordid-hispidulous, 
  

   about 
  1 
  cm. 
  long; 
  heads 
  1.5 
  cm. 
  wide; 
  phyllaries 
  4, 
  deltoid-ovate, 
  obtuse, 
  

   entire, 
  hispidulous, 
  6 
  mm. 
  long, 
  5 
  mm. 
  wide; 
  rays 
  about 
  8, 
  yellow, 
  oval, 
  

   tridenticulate, 
  the 
  lamina 
  joined 
  in 
  a 
  ring 
  at 
  base 
  without 
  proper 
  tube, 
  hispid- 
  

   ulous 
  and 
  stipitate-glandular 
  dorsally, 
  5.5 
  mm. 
  long, 
  2.8 
  mm. 
  wide; 
  disk 
  

   corollas 
  numerous, 
  yellow, 
  the 
  slender 
  tube 
  1 
  mm. 
  long, 
  glandular, 
  the 
  cam- 
  

   panulate 
  throat 
  0.8 
  mm. 
  long, 
  the 
  triangular 
  acute 
  recurved 
  teeth 
  1 
  mm. 
  long; 
  

   pales 
  acuminate, 
  lanceolate, 
  dentate 
  at 
  apex, 
  stipitate-glandular 
  above, 
  about 
  

   3 
  mm. 
  long; 
  fruit 
  turbinate, 
  slightly 
  compressed 
  laterally, 
  densely 
  stipitate- 
  

   glandular 
  throughout 
  and 
  somewhat 
  hispidulous, 
  the 
  body 
  4.5 
  to 
  5.5 
  mm. 
  

   high, 
  4 
  to 
  4.5 
  mm. 
  deep, 
  bearing 
  around 
  the 
  rounded 
  apex 
  5 
  to 
  7 
  subulate 
  

   horns 
  usually 
  grooved 
  on 
  the 
  inner 
  side, 
  the 
  2 
  to 
  4 
  inner 
  ones 
  shorter, 
  spread- 
  

   ing 
  or 
  slightly 
  ascending, 
  1 
  to 
  2 
  mm. 
  long, 
  the 
  outermost 
  one 
  erect, 
  with 
  

   broadened 
  base, 
  2 
  to 
  3 
  mm. 
  high, 
  the 
  one 
  or 
  two 
  lateral 
  ones 
  similar 
  to 
  the 
  

   shorter 
  inner 
  ones. 
  

  

  Type 
  in 
  the 
  Gray 
  Herbarium, 
  collected 
  on 
  Gardner-near-Hood 
  Island, 
  

   Galapagos 
  Islands, 
  September 
  28, 
  1905, 
  by 
  Alban 
  Stewart 
  (no. 
  701). 
  Dupli- 
  

   es. 
  L. 
  Robinson. 
  Flora 
  of 
  the 
  Galapagos 
  Islands. 
  Proc. 
  Amer. 
  Acad. 
  38: 
  238. 
  1902. 
  

  

  