﻿igi6] GATES— PAIRS OF SPECIES 197 



of plants having white berries on slender pedicels or red berries on 

 thick pedicels, and give it as their opinion that such forms are 

 sports and not hybrids. 



Merriam 14 has also made observations on the differences between 

 these two species. He found that A . rubra has very delicate green 

 pedicels, three-quarters of an inch in length, and berries a half 

 larger than A . alba, the pedicels being hollow, so that they are easily 

 crushed between thumb and finger. In A. alba the pedicels are 

 very thick, red, half an inch in length, the berries small (one-third 

 inch), the pedicels being solid or nearly so and not easily crushed. 

 Sometimes the berries in A . alba are red, the difference in color being 

 the only change. This suggests that the white of A . alba may be 

 dominant to red. 



Earlier observations on these species were made by Bigelow, 15 

 who described A. alba independently under the same name, 16 not 

 knowing that Miller had described it previously. 17 He points 

 out several other distinctions between A. rubra and A. alba in his 

 descriptions, which may be summarized as follows: 



pedicels more sparse than slightly pubescent at top 

 the extremities 



Sepals 4. oblong, white, con- Sepals 4, oblong, green, stri- 



