VOL. II  Q  Q


594  A  NATURALIST  IN   THE   PACIFIC

NOTE   6S  (page   264)

On  some  of  the  Hawaiian  Endemic  Genera,  excluding  those   of
the  compositie  and  lobbliaceic

Haplostachys^  Phyllostegia^  and  Stenogyne,  all  Labiate  Genera,—
Phyllostegia  is  not  strictly  peculiar  to  Hawaii,  since  out  of  the  17  species
enumerated  in  the  Index  Kewensis^  15  are  Hawaiian,  i  Tahitian,  and  i  is
accredited  to  Unalaska  (one  of  the  Aleutian  Islands). The  last  locality
appears  to  be  an  error. The  species  in  question  is  P. microphylla,  Benth.;
and  on  looking  up  the  original  authority  in  Linnaa  (vi. 570,  1831),  I  find
the  locality  is  thus  given :  "insula  coralligena  Romanzoffi," which  is  either  one
of  the  atolls  of  the  Paumotu  Islands  in  about  lat. 15^  S. and  long. 144°  W.,
or  a  coral  island  of  the  Marshall  Group,  most  probably  the  former. ... I
paid  some  attention  to  the  suitability  of  the  fruits  of  these  three  Labiate
genera  for  dispersal  by  frugivorous  birds,  for  which  the  fleshy  nucules  in
the  cases  of  Phyllostegia  and  Stenogyne  apparently  fit  them. Out  of  the
fruits  of  five  species  of  Phyllostegia  examined  by  me,  the  seed-coverings  in
three  species,  after  the  removal  of  the  fleshy  covering  of  the  nucule,  were
too  soft  for  the  protection  of  the  seed  in  a  bird's  stomach. Hillebrand  also
observes  (p. 347)  that  the  nucules  when  dried  are  wrinkled,  and  absorb
moisture  easily,  a  quality  which,  if  true  of  all  the  species,  would  make  the
distribution  of  the  genus  by  birds  impossible. However,  in  two  species  I
found  the  seed-coverings  somewhat  harder. It  would  seem  that  since
birds  have  largely  ceased  to  disperse  these  plants,  the  soft-skinned  nucules
would  in  the  absence  of  their  selective  agency  more  frequently  characterise
the  genus. It  is  possible  that  the  dry  nucules  of  Haplostachys,  which
according  to  Hillebrand  are  not  affected  by  drying,  represent  the  original
condition  of  those  of  Phyllostegia,  and  that  the  fleshy  character  has  been
acquired  in  this  archipelago. It  will  be  seen  in  the  list  on  page  263,  that
Haplostachys  is  regarded  by  Gray  as  a  section  of  Phyllostegia. 