193 2 Chromosome numbers in Hemerocallis, with reference to triploidy 251 



The Purely Diploid Species 



Twenty-two chromosomes have been found to be the rule in the 

 early equatorial plates during the mitoses of root-tip cells for all 

 individuals thus far studied of the following species:— Hemerocallis 

 fiava, H. minor, H. Dumortierii, H. Middendorffii, H. aurantiaca, H. 

 Thunbergii, H. citrina, H. Forrestii, H. multifiora, H. nana and H. 

 plicata. In various cases deviations in the number were observed 

 giving counts of 21, 22, 23 and 24 for the same plant. Descriptions 

 with colored plates of all the types of these species which were 

 studied, except for the two named last, have been published (Stout, 

 1929 c, 1930). 



The Species Hemerocallis fulva 



It is now certain that the cultivated horticultural plant described 

 by Linnaeus as Hemerocallis fulva is merely a triploid clon which is so 

 completely self-incompatible that it never produces seeds to self-, 

 close-, or intra-clonal-pollinations. That the original plant of this clon 

 was derived from some diploid species is obvious. A survey of the 

 fulvous daylilies closely related to this Europa Daylily has already been 

 presented by the writer (1929a and b) and this indicates that a somewhat 

 variable wild type of fulvous daylily is widely distributed in China and 

 Japan which maybe considered as the species H. fulva. This group 

 would include the H. disticha of Donn, and the H. longituba of Miquel. 



Living plants, showing a considerable range of minor variations, 

 but all here considered as included in the species H. fulva, have been 

 obtained from various localities in China and Japan. In several cases 

 these plants came from what was certainly wild stock reproducing by 

 seeds. No two plants were exactly alike and seeds were readily 

 obtained by intercrossing. In these plants the normal number of 

 diploid or somatic chromosomes is 22. 



The Europa Daylily. It seems very probable that all of the various 

 cytological studies, at least by investigators in Europe and America, 

 previously reported for " H. fulva" have been made on plants of the 

 one clon, the Europa Daylily. The estimates of the haploid chromosome 

 number, based on the grouping of chromatin units in the reduction 

 divisions, have been 12 (by Strasburger, 1882 ; Timm, 1928), 16 (Tischler, 

 1927), and 24 (Schurhoff, 1926, p. 461). Belling (1925) was the first to 

 interpret the grouping of chromosomes in this plant during meiosis as 

 fluctuating about the number eleven. In the prophases of the second 



