154 CARROLL— ON DEVELOPMENT OF 



number of seeds was greater in the chasmogamous form. The relative 

 number and size of the two types of seed are thus seen to vary considerably 

 among different species. 



II. Experiments and Observations on the Production of chas- 

 mogamous AND CLEISTOGAMOUS FlOWERS 



Observations in the field on the production of cleistogamous flowers 

 show a wide range of conditions under which they appear. In general 

 as was noted above, conditions.. which favor greatest vegetative growth, 

 lead to small production of both kinds of flowers. These conditions 

 seem to be rather dense shade and rootage in soil saturated with fresh 

 running water. Along brooks in light shade or open sunny meadows 

 the plants are shorter and produce chasmogamous flowers in greatest 

 profusion. Before the production of chasmogamous flowers these 

 plants are quite generally to be found bearing abundant cleistogamous 

 flowers and careful examination of the plants during the period of 

 maximum production of chasmogamous flowers will frequently show 

 shorter shaded branches on the lower parts, and these bear cleistogamous 

 flowers. In one such situation where every one of twenty-five plants 

 was examined the cleistogamous flowers were found in the act of pushing 

 off the perianth cap or these caps were found lying on leaves or other 

 parts of the plant. In one station by an open sunny roadside that was 

 under observation during the last week of July and the first week of 

 August, and again during September 1916, chasmogamous flowers and 

 seed were produced in abundance, and cleistogamous flowers which 

 were abundant during June and early July continued more sparingly 

 in the later weeks. Under adverse conditions the production of chas- 

 mogamous flowers is reduced, but that of cleistogamous flowers remains 

 constant as in the early part of the season, or increases. In a station 

 on a hillside in the open woods that was under observation during the 

 spring and summer of 1916, the plants produced abundant cleistogamous 

 flowers from the middle of June to the middle of September. During 

 July and August a few chasmogamous flowers only were produced. The 

 soil during June was rather moist, but during the later summer was 

 quite dry for a depth of two inches. In a bog in the woods at the foot 

 of this hill, pale green plants eight to ten inches high lasted through 

 the summer, producing cleistogamous flowers very sparingly and chas- 

 mogamous flowers not at all. Conditions here were very similar to 

 those in the bog noted above. Four such boggy situations in the woods 

 were under observation during the entire summer. The conditions 



