stout: pollinations in cichorium intybus 361 



METHODS OF STUDY IN CHICORY 



This species is especially favorable for such a study. The 

 species is one of the Composites. All the flowers of each head are 

 ligulate; they are perfect and alike (see plate 30). The flowers 

 open almost simultaneously not only in a single head but in the 

 various heads (from i to perhaps 100) that open in any one day 

 on any one plant. In regard to anatomical development and 

 compatibility the conditions give absolute potential self- and 

 cross-fertility, the only exception in my cultures being a few plants 

 which have appeared that are impotent in some degree. 



Furthermore, an individual flower head is normally open but a 

 few hours and all of its flowers shed their pollen at the same 

 time. As the various heads opening in any one day on a plant 

 or on different plants are quite uniform in this respect, dift'erences 

 in the maturity of sex organs in these flowers are, it w^ould seem, 

 as nearly absent as is possible in any plant. 



The hour of opening and the period during which flower heads 

 remain open varies with the weather conditions and with the 

 season. During a warm sunny period in midsummer the pro- 

 cedure in the experimental plots at the New York Botanical 

 Garden is in general like that recorded for the 31st of July, 1912. 

 On this date, at 6:30 A. M. the flower heads were mostly open 

 but the individual corollas were not fully extended or flattened 

 out and none of the pistils were protruding through the stamen 

 ring. At 6:40 a few pistils were protruding (see plate 30, figs. 

 I and 4) : at 7 :05 the styles of these flowers were fully protruding, 

 but the stigmas were appressed to each other, a stage in which the 

 rough spiny exterior of the style and stigmas drags out consider- 

 able pollen; bumble bees and various other insects began to appear: 

 at 7 :30 the stigmatic lobes began to spread (fig. 7) : at 8 :oo the 

 stigmas of all flowers were fully extended and the lobes separated 

 and strongly recurving (figs. 2, 5, and 9), thus exposing the inner 

 stigmatic surfaces; insects were very busy gathering pollen: at 

 10:00 the petals began to wither, fade, and close in over the pistils: 

 at 10:30 nearly all heads were closed never to open again (fig. 

 3 and 11), This sequence in development is shown in the heads 

 and individual flowers portrayed in plate 30. 



On such a day, only the interval between 7:45 and 9:30 A. M. 



