Oenothera Brevistylis. 315 



closing the flowers in parchment bags ; and fertiHzed them 

 with their own pollen. Since that time the species has 

 proved absolutely constant; and each year I choose the 

 best examples with the smoothest leaves as seed-parents. 



§ II. OENOTHERA BREVISTYLIS. 



This form has been thoroughly investigated and de- 

 scribed by Julius Pohl.^ I have used it mainly in hy- 

 bridization experiments, in which it behaves in a different 

 way from all other species in the group of the evening 

 primroses. I shall deal here only with its external char- 

 acters, with its first discovery in the field and with its con- 

 stancy. This species, which is very easily recognized dur- 

 mg its flowering period, has never arisen in my cultures. 



In the rosette stage and in fact at any time before it 

 flowers, it is difficult to distinguish. Its more rounded 

 leaves give it a slightly different appearance; and in hy- 

 brid cultures it is often possible before any stems have 

 been developed to predict whether there will be many or 

 few brevistylis. But it is not until the flower buds appear 

 on the stem that the difference between it and other forms 

 becomes clearly discernible, and that one can record them 

 with safety. The young inflorescence forms a rosette of 

 rounded leaves on the top of the stem in O. brevistylis 

 and of pointed ones in O. Lamarckiana. Shortly after- 

 wards the buds appear; they are shorter, thicker and 

 blunter than the slender conical ones of the parent spe- 

 cies. Then the flowers open, just as large and just as 

 beautiful as in Lamarck's Evening Primrose. At first 

 sight it looks as if they had neither a style nor stigma; 



* Julius Pohl, Ueher Variationsweite bei Oenothera Lamarckiana, 

 Oester. bgt. Zeitschrift, Jahrgang 1895, Nos. 5 and 6, Tafel X. 



