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SCIENCE. 



[N. S. Vol. I. No. 14. 



skilful and diligent visitors, have played 

 the chief part in the evolution of flowers ; 

 we owe to them the most numerous, most 

 varied and most specialized forms." The 

 Lepidoptera have given rise to some highly 

 specialized flowers, but I think it would be 

 hard in a single case to show a probability 

 that the incipient stages of irregularity 

 were induced by their visits. 



That the less specialized flowers are 

 spring flowers is only true in a general way. 

 From my present data it appears that the 

 maximum of the entomophilous Choripeta- 

 Ite is in August, though further observa- 

 tions may show a greater number in spring. 

 Including the anemophilous species, the 

 Choripetalse will certainlj^ show an early 

 maximum, and that is the extent of the 

 justification of their being called spring 

 plants. The same is true of the entomo- 

 philous Monocotyledons. If the blooming- 

 seasons of all of the Monocotyledons of a 

 given neighborhood be worked out, I doubt 

 if they will show a vernal maximum, 

 though the position of Carex may accom- 

 plish this result. The Ganiopetalse have 

 a late maximum, but none of them are free 

 from the competition of the Monocotyledons 

 or the Choripetalse. 



It seems to me that Mr. Harshberger has 

 contributed an important point in reference 

 to the general positions of the flower groups 

 by indicating the influence of the retreat of 

 glacial winter. Making use of this sugges- 

 tion we may suppose that, as the warm sea- 

 sons became longer, a large proportion of the 

 Monocotyledons and Choripetalse moved 

 northward, climbed the mountains or open- 

 ed their flowers early. While the more 

 highly specialized groups were by no means 

 thus relieved from the competition of the less 

 specialized, there can be little doubt but 

 that in the later months they found a time 

 when that competition was less severe. 

 This may aid us in explaining what has 

 struck me as a fact in the phtenological 



habits of the flora of my neighborhood. I 

 have indicated that the introduced plants, 

 the aquatics and the degraded entomophi- 

 lous flowers tend to prolong then- blooming 

 seasons, and have supposed that this results 

 from their being more reUeved from the com- 

 petition which besets the other flowers. Al- 

 though the data have not been arranged to 

 test the point thoroughlj^j it has occurred to 

 me that the later plants in general bloom 

 longer than the early ones. (In investiga- 

 ting this proposition, it may be proper to 

 eliminate some of the very late ones, whose 

 seasons are not cut short bj' competition, 

 but by way of preparation for the approach- 

 ing winter.) The later species thus appear 

 to have entered a position where competi- 

 tion was less severe. It may be, however, 

 that they show the effects of competition 

 less, merely on account of their superiority. 



Mr. Harshberger attributes floral modifi- 

 cations to the ' irritating action of insects 

 on vegetal protoplasm.' This suggests 

 Henslow's* theory. As far as I know, 

 that theory has not been accepted by any 

 one who has made a serious investigation 

 of the relations of flowers and insects, and 

 for that reason it has not seemed justifiable 

 to discuss it at length. It seems safe to 

 say that it has not been shown that direct 

 insect contact will induce floral modifica- 

 tions, or that the theory will account for 

 the most ordinary facts of floral structure. 



Finally, with regard to the literature, I 

 notice that Mr. Harshberger quotes Mae- 

 Millan (1. c.) without giving references. 

 On consulting this author, I find that the 

 general proposition of the early blooming of 

 the less specialized plants and the late 

 blooming of the more highly speciaUzed is 

 at least strongly suggested, and that too 

 evidentlj^ on the authority of persons cited 

 in a bibliographical list. The autumn- 

 flowering of the Composite is distinctly 

 stated. From his observations in Flanders, 



* The Origin of Floral Structures, 1888. 



