642 Anderson and Schafer. — Species Hybrids in Aquilegia. 



somal differences in the genus. Aquilegia is, therefore, one of those genera 

 like Ribes, in which sizes, shapes, and numbers of the chromosomes remain 

 relatively constant in spite of great external differentiation between the 

 species. 



The work reported below was begun independently by the senior and 

 junior authors at the Missouri Botanical Garden and the John Innes Horti- 

 cultural Institution respectively. In each case material of as many species 

 as possible was obtained from seedsmen and botanic gardens, and a number 

 of crosses were made. Experience has proved that practically all of this 

 material is unreliable for precise work, and the study is being repeated with 

 authentic material. The following crosses, however, were considered worthy 

 of a preliminary examination, and it is with the results obtained from them 

 that the present paper is concerned. 



A. vulgaris compacta X A . formosa (1). 



A. caertilea x A. vulgaris (2). 



A. ecalcarata x A. chrysantha (3). 



A. ecalcarata x A, vulgaris compacta (4). 



A. chrysantha x A. vulgaris ' China Blue' (5). 



A. vulgaris x A.Jaeschkani (6). 



A. vulgaris x A. chrysantha (7). 



A. vulgaris X A. canadensis (8). 



Certain regularities of interspecific dominance were apparent even in 

 this material. They can be roughly summarized by saying that all of the 

 first generation hybrids were more like Aquilegia vulgaris (in the broad 

 sense) than might have been expected. This was true even when .<4. vulgaris 

 was not one of the parents. Similar results have been obtained by other 

 investigators. Cockerell (2), for instance, crossed two American species, 

 A. chrysantha and A. desertorum. As regards the hybrid he wrote : ' the 

 form of the flowers departs from both parents in the direction of the A . vul- 

 garis group '. In none of the cases in the literature, however, were enough 

 different crosses attempted to suggest that the 'vulgaris' appearance of the 

 Fj was a general phenomenon. It maybe mentioned, however, that it is a 

 common experience of those who grow Aquilegia as a garden flower that 

 the vast majority of seedlings from natural seed have the appearance ot 

 vulgaris. 



Three of the most interesting crosses are illustrated in Fig. 2. The 

 parents used were : 



I. A. ecalcarata, Maxim, (with practically no spur). 



3. Garden varieties of an American long-spurred species. 



3. A garden variety oi A. vulgaris (medium spurred). 



In contrast to the great differences between the parents is the remark- 



