284 



BOTANICAL GAZETTE 



[OCTOBER 



over-favorable conditions, in the same degree 

 the autumnals claim possession of that less 

 suitable period during the closing days of 

 vegetative activity, and for similar reasons. 

 Each group has been able on account of 

 peculiar characteristics to work into and 

 occupy these periods unsuited for plants of 

 less xerophytic tendencies, as their periods 

 of growth and reproduction fitted into these 

 seasons of the year, extremes in each case, 

 where the great majority of forms could 

 not succeed. As floral activity is more 

 definitely restricted than vegetative, which is 

 largely accomplished in earlier periods, it is 

 also evident that the problems of pollination 

 and seed dissemination must have been no 

 small factor in working out through selec- 

 tion the floral restriction of these forms. 



The following species extend over from 

 the serotinal aspect, but are rendered incon- 

 spicuous by the overtopping layer of a few 

 autumnal species : Verbena stricta, Carduus 

 undulatus, Ratibida columnaris, Meriolix 

 serrulata, Polygala alba, and Lygodesmia 

 juncea. They become less and less conspi- 

 cuous as the period advances. 



As ruder als we may note Melilotus alba, 

 coming over from earlier aspects, Lactuca 

 canadensis, and Salsola tragus. 



Conditions here are but the continuation 

 and accentuation, during the early part of 

 the aspect at least, of those of the serotinal. 

 The maximum conditions there noted become 

 less pronounced toward early September, and 

 toward the middle of the month pass 

 gradually into those more settled condi- 

 tions of early fall in which maturation is 



