276 TWIN HYBRIDS OF OENOTHERA HOOKER! T. AND G. 



In the first named culture a mutant occurred, which was an Oe. 

 oblonga and became a large rosette, but did not develop a stem. 

 Moreover in this culture about one-half of the specimens of velutina 

 showed a pale yellowish tinge, which caused them to grow slowly 

 and to produce only small, late flowering stems. In both the other 

 cultures the velutina were dark green and as stout as the laeta. In 

 this respect Oe. franciscana shows a complete parallelism with Oe. 

 Hookeri, since the velutina, derived from this species as a pollen 

 parent, are also for a large part yellow and weak, whereas those 

 from the reciprocal crosses are always dark green (Gruppenweise Art 

 bildung 1913, p. 131 and p. 116, fig. 46). 



Apart from this special feature the velutina of the three crosses 

 exactly resembled one another, and so did the laeta. At the time of 

 flowering they were one of the most beautiful groups of my garden. 

 The flowers of both twins are as large and as bright as those of Oe. 

 Lamarckiana, the foliage of laeta is bright green, whereas that of 

 velutina is brownish or almost red. The spikes and flower buds of 

 the first are also green, but those of the latter are dark red. The 

 differentiating marks were the same as in the corresponding hybrids 

 of Oe. Hookeri. The leaves of the laeta were grass green and broad, 

 those of the velutina dark green and narrow and more or less folded 

 along their mid-vein. The spike of the first is loose, whereas on the 

 latter the flowers and fruits are more densely crowded. The flower 

 buds of the laeta are thin and have only some few red spots, but 

 those of the velutina are thick and almost uniformly red. The pollen 

 is pale yellow and spare in the first type, but in the second it is 

 richly developed with long threads of viscin and almost white. The 

 whole plants are glabrous in the first case, but hairy in that of 

 velutina. From these and other marks we see that the similarity of 

 these twins to those of other crosses of Oe. Lamarckiana is very 

 striking. 



I self-fertilized some specimens of each of the six types, sowed their 

 seeds in 1917 and cultivated 58—60 specimens from each parent 

 until the period of ripening their first seeds. I counted the pacels 

 in August, when almost all the plants were in full flower, and got 

 the following figures: 



