250 Cytologia 3 



Chromosome Numbers in Hemerocallis, with Reference 

 to Triploidy and Secondary Polyploidy 



By A. B. STOUT 

 The New York Botanical Garden 



Received February 22, ig32 



The condition of triploidy in certain members of the fulvous daylilies 

 has been reported by Belling (1925) and by Takenaka (1929). Evidently 

 Belling studied the Linnaean type of the species Hemerocallis fulva 

 that has long been propagated asexually as a garden clon in Europe and 

 America and for which the writer (1929 a) has suggested the horticul- 

 tural name " Europa Day lily ". Takenaka reported triploidy in what 

 he calls the H. fulva of Linnaeus, in a double-flowered clon which he 

 calls H. disticha var. Kwanso, and in another but unnamed type. Both 

 Belling and Takenaka agree that the triploid number in the plants 

 they studied is 33 and their assumption is that there are three sets of 

 11 each. 



Takenaka also reports a diploid number of 22 for plants of H.flava, 

 which is in agreement with the number reported by Nawaschin (see 

 Tischler, 1927), and for plants considered as H. aurantiaca Baker, H. 

 Middendorffii Traut. and Mey., H. disticha Donn, H. longituba Miq., 

 and H. minor Miller. 



A rather extensive survey of the chromosome numbers has now 

 been made by the writer* for the species, several clonal varieties, and 

 various seedlings of Hemerocallis assembled at The New York Botanical 

 Garden which shows (1) that a somatic number of 22 chromosomes is 

 the rule for all species of the genus, (2) that triploidy exists in several 

 of the cultivated clons of fulvous daylilies, and (3) that diploids, 

 triploids, aneuploids and para-triploids are to be obtained among the 

 seedlings of diploids crossed with triploids. 



* The author is indebted to assistants for the preparation and preliminary study 

 of the cytological material and especially to Miss Clyde Chandler, technical assistant 

 to the writer. 



