304 PROCEEDINGS OF THE ACADEMY OF [1893. 



ing adnate with the ovarium formed the akene, but that one of 

 these became wholly absorbed before the final growth of the struc- 

 ture. The scales are the dilated bases of leaves, aud the awns abor- 

 tive petioles or laminre. When but two awns remaiu, it is simply 

 the result of the total or partial suppression of three of the original 

 members of the five-leaved verticil. * 



Rhythmic Growth in Flowers of Heliopsis l^evis. 



It must be well known to observers that the column of stamens 

 in many Composite is drawn up far beyond the mouth of the floret 

 by the advancing pistil, and that subsequently it descends, and is 

 included in the floret. I believe I am the only one who has called 

 particular attention to this behavior in Composite, though others 

 before me have noted a shrinking tendency in the filaments of 

 some Ckicoracese, which has been attributed to an irritable habit. 

 Noting in a large mass of Heliopsis Icevis growing near my 

 house in Germantown that the elevation and depression of the 

 staminal column occurred at stated hours during the day, I started 

 on the 16th of August to devote observations several times a day 

 for a week to an examination of the behavior of the flowers. 



The first observation was that of the hundreds of flower-heads 

 that had flowered during the summer season, not a floret could be 

 found infertile. This with me is indicative of self-fertilization. 

 But I believe it is conceded by all biologists who have given atten- 

 tion to this large order of plants, Compositse, comprising a tenth 

 part of the vegetable kingdom, that the florets are mostly self-fertil- 

 izers. Where there is a tendency to dioecism, and where there are 

 ray florets pistilliferous only, these — the very small minority — must, 

 of course, have florets requiring aid in pollination from other 

 flowers. The most that has been claimed for Composite is 

 that they are " adapted to cross-fertilization ;" but even this state- 

 ment is derived from a theoretical conception of the plant's behav- 

 ior, for every practical test made by excluding insects has found 

 the florets just as fertile as if insects had been allowed free access to 

 them. It was, however, well worth while to keep this topic in view 

 while making my notes. The date of the observations is given, 

 as I have a suspicion that the phases of growth are not iden- 

 tical in different seasons or localities, though the uniformity goes on 

 with tolerable regularity. 



