64 GENETICS 



7. Lamarck's Evening Primrose 



The most widely known plant mutations are the 

 progeny of Lamarck's evening primrose, Oenothera 

 lamarckiana, because it was these plants that led 

 de Vries to formulate his mutation theory. 



It is believed by botanists in general that this 

 plant is a native of the southern United States, al- 

 though it is now, so far as is knowm, extinct as a 

 wild species in America, and native specimens are 

 included in but few American herbaria. 



It was exported to London as a garden plant about 

 1860, and from thence it spread to the continent, 

 where, escaping from gardens, it became wild in at 

 least one locality neg.r Hilversum, a few miles from 

 Amsterdam. Here, in an abandoned potato field, 

 it fell under the seeing eye of Hugo de Vries in 1885, 

 and now both botanist and primrose are famous. 



De Vries found among these escaped plants not 

 only 0. lamarckiana, but also two other kinds 

 or mutants, 0. brevistylis, characterized by short- 

 styled flowers, and 0. Ice vi folia, w^iich has smooth 

 leaves. These tw^o were entirely new species hitherto 

 unknown at the great botanical clearing-houses of 

 Paris, Leyden, and the Kew Gardens. 



Since the seeds of the (Enothera are produced by 

 self-fertilized flowers, de Vries felt safe in regard- 

 ing these plants as mutants rather than hybrids, 

 and he continued to study them with especial care. 

 Transplanting the mutants along with representa- 

 tives of 0. lamarckiana to his private gardens in 



