IOWA ACADEMY OF SCIENCES. 165 



These records may be compared with the phenological 

 notes for Ames and Armstrong. The former in central 

 Iowa and the hitter in north central Iowa. 



AMES. ARMSTRONG. 



Ma}^ . June 18. 



Crataegus mollis SaLsola Kali var 7 ragiis 



May 7. Acerates viridiflora 



Aquilegia CanadeJisis Asclepias tubeyosa 



Primus Virginiana Linwn ustliatissitmnn 



Fragaria Virginiana Svinphoricarpos occidentaitis 



Lnthyrus venosus 

 Ructbeckia hirta 



Unfortunately there are but few representatives of the 

 same species from these different localities. The Crata'cjus 

 mollis, Aquilegia Canadensis, Pniiius Virginiana and Fragaria 

 Virginiana^ are nearly a week later in Ames than in Mis- 

 souri Valley and Crescent. These points are slightly south 

 of Ames, but not enough to materially influence the period 

 of flowering. The loess region along the Missouri river is 

 distinctly "warmer than central Iowa, w^iich is distinctly 

 influenced by the cold and impervious soil. The imper- 

 vious nature of the soil is shown by the many small lakes 

 and ponds in central Iowa, but nearly wanting in western 

 Iowa. 



While plants are called into activity sooner in Keokuk 

 than in Sioux City, they mature in a relatively shorter 

 period of time in the latter place owing to clearness of the 

 sky, and the drier weather. 



WIND. 



The wind is another most important factor in the devel- 

 opment of the plant life in that region. The tendency of 

 the wind is to increase transpiration so that plants with 

 tender foliage are wanting or occur in the canons or 

 wooded ravines. The wind has such an erosive action that 

 stones may become polished as in the boulder here shown 

 resting on the drift. The writer has seen clouds of dust, 

 carried high in the air, last for several days. Such dust 

 settling on plants cannot but be injurious in checking the 



