24 BOTAMCAL GAZETTE [january 



them it is the most like 0. (LamarckianaXO. biennis Chicago) 

 velutina, without the marks of the second parental species, however. 

 It is slender, with long internodes in the spike, and with flowers as 

 large as those of O. Lamar ckiana. 



5. 0. Lamar ckiana mut. velutina is distinguished from its parent 

 species in a very striking character. It has lost the property of 

 producing about one-half of empty grains; almost all of its seeds 

 contain healthy and well developed germs and germinate easily. 

 This new quality is dominant over that of the parent. It is the 

 same as in almost all the older species of the genus. 



6. Moreover, O. mut. velutina is distinguished from O. Lamarck- 

 iana at least in one other dominant character, the smoothness of 

 its leaves at the time of flowering. Secondly, it is distinguished 

 in quite a number of characters, which seem to be more or less 

 independent of one another, namely, slender stature, long inter- 

 nodes of the flower spike, narrow and longitudinally folded leaves 

 and bracts, and cup-shaped flowers. Besides these, the richness 

 in red color and the hairiness of all organs, especially in their youth, 

 are very striking marks. 



7. In crosses with those species which split O. Lamar ckiana and 

 some of its other derivatives into the twin hybrids laeta and velu- 

 tina, the O. mut. velutina produces only hybrids of the velutina type. 



8. In crosses with O. Lamar ckiana and O. nanella, these forms 

 are seen to be split by O. mut. velutina into twin hybrids, which 

 correspond to the twins produced by other species with them, but 

 which, of course, lack the characters of those other parents. The 

 twins of 0. blandina may be considered as pure laeta and pure 

 velutina, therefore, the former having smooth leaves and bracts 

 in the summer, the latter being identical with O. blandina itself. 



9. The study of our new mutant reveals the existence of at least 

 two recessive characters in 0. Lamarckiana, namely, the bubbles 

 of the leaf blade and the presence of typical empty seeds. 



Botanic Garden 

 Amsterdam 



EXPLANATION OF PLATE I 



At the right, Oenothera Lamarckiana mut. velutina (O. blandina) ; at the 

 left, O. blandina mut. spiralis. 



