Am.  Jour.  Pharm. 
April,  1921. 
Hybridization  in  Plants. 
249 
ORIGINAL  PAPERS 
HYBRIDIZATION  IN  PLANTS  * 
By  Heber  W.  Youngken,  Ph.D., 
PHILADELPHIA,  PA. 
The  term  hybrid  is  a  derivative  of  the  Greek  word,  an 
outrage  or  insult,  and  a  hybrid  was  regarded  by  many  of  our  an-^ 
cestors  as  an  outrage  on  nature. 
Hybridization,  according  to  older  definitions,  was  defined  as 
the  intercrossing  of  two  recognizably  different  species,  the  resulting 
product  being  therefore  spoken  of  as  a  hybrid.  The  term  mongrel 
was  applied  to  the  crossing  of  two  varieties  of  the  same  species ;  but 
so  many  graded  connections  between  the  two  have  been  shown  to 
exist  that  the  term  "hybrid"  now  exists  in  common  use  to  cover 
every  case. 
In  thinking  of  degrees  of  similarity  or  difference  between 
parent  forms  in  relation  to  their  offspring,  it  is  well  to  bear  in 
mind  that  diverse  types  of  plants  in  many  respects  may  characterize 
members  of  the'  same  species.  Thus,  the  staminate  plants  of 
Lychnis  vespertina  and  Lychnis  diurna  differ  markedly  from  the 
pistillate  plants  in  height,  vigor  and  thickness  of  stem  and  in  hair- 
ness  and  size  of  leaves,  apart  from  the  doecious  sexual  relation. 
Again,  dimorphic  plants  like  the  primroses  and  partridge  berry 
and  trimorphic  plants  like  the  purple  loosestrife,  while  usually 
resembling  each  other  in  vegetative  parts,  differ  strikingly  in  the 
structure  of  androecium  and  gynoecium. 
Moreover,  in  the  genus  Catasetum  of  the  Orchidacce,  plants 
sent  successively  from  South  America,  were  described  when  they 
flowered  as  three  genera  under  the  names  "Catasetum,"  "Mona- 
cantha,"  and  (CMyanthus.,}  In  time  it  was  shown  that  the  totally 
distinct  forms  of  flower  represented  staminate,  pistillate  and  herma- 
phrodite examples  of  the  same  species. 
In  considering  possible  hybridization  and  the  degree  of  resem- 
blance and  difference  shown  by  parents,  such  facts  as  mentioned 
*Philadelphia  College  of  Pharmacy  and  Science,  January  31,  1921. 
