126 BOTANICAL GAZETTE 



AUGUST 



(10206 and 10207) were produced by crossing two females grown 

 from the Baden seeds with pollen of a single pure-bred purple- 

 flowered male from Cold Spring Harbor. As Melandrium rubrum 

 has reddish-purple flowers and as this color has been shown to be 

 epistatic to bluish-purple (which may have been carried as a 

 latent character by the white-flowered plants), there was no reason 

 to expect that the F z progeny of any of these five crosses would 

 present any noticeable difference in flower-color from that of their 

 M. rubrum parent. This expectation was realized, the 262 off- 

 spring from these crosses all having reddish-purple flowers. The 

 young plants in these families were generally indistinguishable 

 from pure-bred M. rubrum, but later they differed by being notably 

 more vigorous, having enormous rosettes of broad, shining, dark- 

 green leaves. They were also much more easily grown as annuals 

 by early sowing, being in this regard intermediate between the 

 parents. Almost all of the hybrids were blooming by the middle 

 of July, before the first flowers of any pure M. rubrum had opened. 

 Compared with these crosses between Melandrium rubrum and 

 the Cold Spring Harbor plants, a cross of M . rubrum with M. album 

 gave a totally different and unexpected result. A mating between 

 a female of the white-flowered album and a purple-flowered male 

 rubrum produced an F t (10201) consisting of 23 white-flowered 

 individuals and 3 (probably 4) purple-flowered ones. The white- 

 flowered plants were unlike either parent in vegetative characters, 

 having relatively short, sharp-pointed, grayish-green leaves which 

 were strongly ascending in the fully developed rosette, while 

 both parents have long, spreading, dark-green leaves. The flowers 

 were not only white like those of their white-flowered mother, but 

 they were also nearly identical with them in form. It was noted 

 that rarely some of the flowers became faintly and unevenly 

 streaked and washed with purple just as they were fading, a 

 feature never observed in the flowers of any of my other white- 

 flowered plants. These white-flowered hybrids were a little later 

 in blooming than their white-flowered parent, but were still easily 

 induced by early sowing to behave as annuals. The purple- 

 flowered offspring of this cross were of an altogether different 

 character, and were not readily distinguishable in rosette and 



