i78 
The  Genus  Eucalyptus. 
/Am.  Jour.  Pharm. 
(.       April,  1904. 
having  already  appeared.  Baker  and  Smith 1  have  published  a 
large  monograph  on  the  genus,  their  work  having  special  regard  to 
the  essential  oils  yielded  by  the  various  species,  and  Alfred  James 
McClatchie  has  published  an  interesting  monograph2  on  the  euca- 
lypts  cultivated  in  the  United  States. 
The  genus  Eucalyptus  was  named  by  L'Heritier  in  1788,  from  the 
two  Greek  words  meaning  "  I  cover  well,"  "  in  allusion  to  the  opercu- 
lum or  lid  which  covers  the  calyx  until  the  stamens  are  fully  formed." 
The  plants  are  evergreen  and  vary  from  shrubs  to  trees  of  enor- 
mous height,  probably  some  of  them  being  the  highest  trees  known. 
Kerner3gives  the  height  as  140  to  152  metres.  The  leaves  fre- 
quently vary  in  shape  and  in  position  on  both  young  and  mature 
trees ;  they  are  fixed  vertically,  and  not  horizontally  as  the  leaves  of 
our  trees,  the  petiole  being  twisted.  The  leaves  furthermore  contain 
large  oil-secreting  reservoirs.  The  flowers  are  arranged  in  cymes 
or  axillary  umbels  and  are  devoid  of  petals  ;  the  usually  whitish 
stamens  are  inflexed  in  the  bud  and  expand  when  the  operculum  is 
removed,  giving  the  name  as  already  stated  to  the  genus.  The 
fruit  is  a  3.  to  6-celled  truncated  capsule,  or  pyxis.  The  seeds  are 
small  and  very  numerous,  the  sterile  ones  predominating;  this  is  no 
doubt  one  reason  why  there  has  been  so  much  difficulty  in  pro- 
ducing seedlings.4 
With  a  genus  of  so  many  species  and  numerous  varieties  it  was  to 
be  expected  that  there  would  be  considerable  confusion  in  regard  to 
the  accurate  determination  of  its  members.  Tate  and  Luehman 
give  prominence  to  the  fruit  for  purposes  of  classification.  Maiden, 
however,  says  that  all  of  its  characters  display  a  puzzling  amount  of 
variation,  and  concludes  that  for  herbarium  work  the  best  charac- 
ters are  afforded  by  the  anthers  and  fruits  ;  whereas  the  scientific  for- 
ester will  be  largely  guided  by  the  nature  of  the  bark  and  timber. 
Baker  and  Smith,  in  addition  to  morphological  characters,  base 
their  deductions  on  the  chemical  properties  and  physical  charac- 
ters of  oils,  dyes,  kinos,  etc.    These  authors  have  probably  the  most 
1  Richard  T.  Baker,  Curator  and  Economic  Botanist  of  the  Technological 
Museum,  New  South  Wales  ;  and  Henry  G.  Smith,  Assistant  Curator  and 
Chemist  of  the  Technological  Museum,  New  South  Wales. 
2  This  is  Bulletin  No.  35,  of  the  Bureau  of  Forestry  of  the  U.  S.  Department 
of  Agriculture. 
3  "Natural  History  of  Plants,"  Vol.  I,  p.  722. 
i  McClatchie,  loc.  cit.y  p.  44. 
