2 ANNALS NEW YORK ACADEMY OF SCIENCES 



INTRODUCTION 



Plants of the single-flowered fulvous daylily, commonly and widely 



cultivated as Hemerocallis fulva, arc decidedly sterile by an abortion 

 of the majority of both the microspores and the macrospores. It is the 

 cytological study of the nuclear phenomena associated with this sexual 

 impotence thai is to lie reported in this paper, and this study has be- 

 come chiefly an analysis of the behavior of the chromosomes and of 

 their multiplication not only in meiotic divisions but in somatic mitosis 

 as well. 



In considering the significance of the cytological data from these plants, 

 it should he remembered that all the plants of this particular type of 

 daylily are propagated, and evidently always have been propagated, only 

 by vegetative means. This is necessary because for them there is a com- 

 plete incompatibility between such of the germ cells as are functional. 

 Evidently the many plants of this one type of daylily, which are now 

 growing rather widely throughout the world either as a cultivated plant 

 oi' as a frequeni escape, constitute a single clon. The various cytological 

 studies that have thus far been reported for plants named as Ileniero- 

 callis fulva involve, it appears, only plants of this commonly cultivated 

 single-flowered clon and hence relate to the various branches of one seed- 

 ling plant. 



Two double-flowered types of the fulvous daylily. deserihed as var. 

 I\ ininso and var. flore-plmo, that are obviously very closely related to 

 the single-flowered clon, are also in cultivation. Single-flowered plants 

 presumably belonging to this same species are to he found growing 

 wild in the Orient. Some of these, such as the //. fulva clon RIaculata 

 have more recently been introduced into garden culture. During the last 

 lew years a considera hie number of plants of the wild storks of this spec it- 

 have been obtained directly from Japan and China and are being grown 

 ;it The New York Botanical Garden for study and for use in breeding 

 (Stout. 1925). Thus far all such plants have been observed to diffei 

 in some particular from plants of the commonly cultivated single-tlowered 

 clon thai is known ;is //. fulva, although in some of these plants the 

 differences are slight. The plants of these wild stocks also differ among 

 themselves. Thus it appears that the species to which this clon is most 

 closely related and in which it is evidently to he included comprises 

 several variel tea or race-. 



The plants of the type commonly cultivated and widely known as //. 

 fulva are. so Ear as we are able to determine, uniform to an unusual 



decree. Living plants of this type obtained Erom such widely separated 



