NOTES AND COMMENT 185 



Fob. 1919). The conditions become more mesophytic with increasing 

 altitude and the temperatures of air and soil at 11,000 ft. range from 

 48° to 58°F. in July and August. The entire flora of the dry glass- 

 lands is tabulated so as to show the occurrence of each species in the 

 five 1 altitudinal zones commonly recognized. There is considerable 

 similarity between the base of the mountains and the montane zone, 

 but very few species of the former region reach the alpine zone. A 

 number of species found only in moister situations at the lower alti- 

 tudes are found to enter the dry grasslands at higher elevations, on 

 account of the influence of lower temperature as well as of the higher 

 soil moisture at the commencement of the growing season. 



Dr. M. J. Dorsey, of the Minnesota Experiment Station, has con- 

 tributed a paper to the Journal of Agricultural Research on the relation 

 of w T eather to fruitfulness in the plum, showing that rain, low tempera- 

 tures and strong wind all interfere with the setting of fruit. Rain 

 interferes with the dissemination of pollen by closing the anthers or 

 preventing them from opening. Frosts injure the pistil more than the 

 pollen, but the chief effect of low temperatures is in retarding the 

 growth of the pollen tube. High wind interferes with insect action and 

 is not in itself capable of effecting full pollination. The fact that plum 

 pollen will retain its germinating power for six months, if kept under 

 favorable moisture and temperature conditions, suggests the possibility 

 of artificial pollination in certain cases. 



