1932 Chromosome numbers in Hemerocallis, with reference to triploidy 255 



Undetermined Types of Daylilies 



Several groups of daylilies grown from seeds or from divisions 

 obtained from various sources in the Orient are not readily to be 

 assigned to any of the species now known. Some of these may be 

 selections of horticultural origin that are being cultivated as clons but 

 several plants were obtained from seeds collected in the wild. In all 

 of these plants thus far studied the chromosome number is almost 

 uniformly 22 except for one plant in which valid counts of 22, 23 and 24 

 were made. 



Named Horticultural Clons 



Chromosome numbers of 22 have been found to be the rule in the 

 root-tip cells of the following clonal varieties :—aurantiaca Major, 

 Aureole, Luteola, Mikado, Mulleri, Sirius, and Vesta. The study of 

 chromosome numbers in the various clons in cultivation is being 

 extended. 



Summary and Discussion 



The normal or most usual number of chromosomes in the somatic 

 cells of all the species of Hemerocallis now known is 22. But several 

 clons of the fulvous daylilies in cultivation or growing as escapes from 

 cultivation are triploids and at least in certain of these there is 

 considerable variation in the number of chromosomes, both in somatic 

 cells and in the various cells involved in sporogenesis. 



The triploid clons comprise (I) the single-flowered (1) Europa Day- 

 lily and the (2) Maculata Daylily, and (II) the double-flowered types 

 known under the names (1) Kwanso, (2) Flore Pleno, and (3) Variegated. 

 All of these are noticeably similar in vegetative habits and in the 

 color of the flowers, and they all obviously belong to the somewhat 

 variable wild species H. fulva. Whether these types have a common 

 origin from a single triploid or a separate origin is not definitely known. 

 There are slight but consistent differences between the Europa Daylily 

 and the Maculata Daylily in habit of growth, in the precise character 

 of the flowers, and in the season of flowering, and these two daylilies 

 differ from the double-flowered types especially in having single flow- 

 ers. It is possible that such differences may have arisen by somatic 

 variations during a long period of clonal propagation, but it is also quite 

 possible that the Europa Daylily, the Maculata Daylily, and the double- 

 flowered type arose as different seedlings. Yet these clons are fully 

 cross-incompatible, and it would seem that there is a close relationship 



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