137 

 SOME WESTERN COLl'MBIXES 



By T. D. a. Cockerell 



Last year (Contrib. U. S. Xat. Herbarium, 20: Part 4) Mr. E. 

 B. Payson published a most interesting revision of the genus 

 Aquilegia as found in North America, and this will naturally 

 serve as a point of departure for new investigations. The sub- 

 ject is a difficult one, owing to the fact (as it seems to be) that 

 any species in the genus will freely cross with any other; and, at 

 least in our experience, the hybrids themselves are perfectly 

 fertile. Thus, on grounds similar to those which convince us 

 that there is only one living species of Homo, it may be main- 

 tained that there is possibly only one genuine species of Aquilegia. 

 Nor is this all ; just as Bursa bursa-pastoris var. heegeri (commonly 

 called Bursa heegeri) is a form lacking the most prominent 

 character of the genus to which it belongs,* so Aquilegia vulgaris 

 var. stellata and A . caerulea \'ar. daileyae lack the generic character 

 of spurred petals, so that but for their obvious general affinities 

 we might not regard them as columbines at all. This plasticity 

 is remarkable in a genus which in many respects seems highly 

 modified. The long spurs are adapted to the visits of butter- 

 flies, but I have seen a bumble-bee (Bombus) slit up a spur from 

 the side, and thus get at the nectar illegitimately. The colum- 

 bine in which this occurred was A. caerulea. Mr, Payson sug- 

 gests that "the modem species of Aquilegia seem to have been 

 developed from species having blue flowers. These seem first 

 to have given rise to white-flowered, these to yellow-flowered, 

 and these finally to red-flowered species." There is apparently 

 no basis for such an evolutionary sequence, for the yellow in 

 the flowers is due to plastids, readily visible under the microscope; 

 while the blue and red are equally due to anthocyanins, held in 

 solution in the sap. Gaston Bonnier, in his scheme of relation- 

 ships of Ranunculaceous genera, indicates an affinity between 

 Aquilegia and Helleborus, while the latter leads back to Caltha, 

 etc. The suggestion might be, that the original columbines were 



* For a good figure, see Shull, Zeits. f. indukt. Abstamm. u. Vererbungslehre. 

 12:98. 1914. 



