28 



usually remain semi-open until after daylight. They close some- 

 what later than the flowers of the Europa Daylilv but are 

 usually fully closed by 9 p. m. 



The various plants of the species Hemerocallis fulva and H. 

 aurantiaca bloom in midsummer, when the temperatures are gen- 

 erally high. Of the daylilies which bloom in May and early June, 

 the H. Dumortierii is also diurnal. Its flowers usually open after 

 sunrise and they close about dark or soon thereafter, but some- 

 times the closing is delayed until 9 p. M. or later. 



The nocturnal flowering is fully developed in the species H. 

 citriiia, which blooms during midsummer. The rule is that the 

 sets of flowers open shortly before sunset, or at least before it is 

 dark, remain widely open all night, and close the following morn- 

 ing soon after daybreak. During cool and cloudy weather the 

 flowers remain open during a part of the forenoon or occasionally 

 well into the afternoon. 



In what may be called "extended flowering," the sets of 

 flowers often remain open for as many as 30 to 50 hours. This 

 habit is exemplified in the clon of H. flava observed by Parkin- 

 son and now commonly known as the Lemon Daylilv or the 

 Custard Lily. The writer has made observations on the flower- 

 ing of this daylily at various hours of the day and night over a 

 period of several years. 



The Lemon Daylily is among the earliest of the daylilies to 

 bloom in spring. As a rule during days of warmest weather the 

 sets of flower^ begin to open in the late afternoon, become fully 

 or almost fully open about sundown or shortly before, and remain 

 expanded during that night, the following day, and until about 

 the following midnight. Cooler weather retards the opening 

 of sets until the following forenoon or midday and if such tem- 

 peratures continue the flowers may remain open through two 

 periods of daylight and the intervening night. Apparently the 

 sudden advent of cooler weather has a somewhat less retarding 

 effect on the closing of the older set of Mowers than it has on 

 the opening of the next set in sequence. As a rule, during the 

 warmer weather there are two sets of flowers open each evening 

 from about (> until near midnight, and but one set open during 

 the hours of daylight. During periods oi unusually low tempera- 



