proceedings: botanical society 265 



It was discovered that the condition absolutely necessary for the 

 perfect development of the reproductive parts is a period of restrained 

 growth in the bud rediments of seedlings, or the buds in the crown of 

 so-called mother beets. While in general this condition is brought 

 about by low temperatures (a mean temperature of 38 to 45°F. appar- 

 ently being required for the sugar beet) when prevailing for several 

 weeks, the necessary degree of growth inhibition may be brought about 

 by other factors, such as pathological conditions, drouth, starvation. 

 The withdrawal of such a period of inhibited metabolism, according to 

 degree, will result in the greater or less degree of approach to foliage 

 conditions, as opposed to the development of reproductive parts. 



Thus, by a study of climatic conditions, suitable locations where the 

 production of seed may be assured, can be selected with a considerable 

 degree of certainty. The proper time to plant the mother-beets can 

 also be indicated, so that we may be reasonably certain that the beets 

 will produce seed. 



This necessity for a period of inhibited metabolism, and the fact that 

 it may be brought about by the conditions mentioned, may explain 

 the remarkable inflorescence of moribund fruit trees, or of trees that 

 have been girdled, also the abnormal behavior of plants carried from a 

 cool to a warm climate. 



The 87th regular meeting was held on February 25, 1913, at the 

 Hotel Cochran. This was the regular annual opening meeting of the 

 Society. Fifty members and forty-two guests were present. 



The retiring president, Mr. W. A. Orton, delivered an address entitled 

 Environmental influences in the pathology of Solanum tuberosum. This 

 paper was published in this journal 3: 180. 1913. 



The 88th regular meeting was held on April 1, 1913, at the Cosmos 

 Club. 



Mr. James T. Jardine was elected to membership. 



The following papers were presented. 



Dr. G. G. Hedgcock: N'otes on Diseases of Trees Causedby Mistletoes. 

 Mistletoes are found only on conifers in northern and northeastern 

 United States; only on angiosperms in southeastern and southern por- 

 tions ; and on both in western and southwestern regions, where they are 

 the most widel}^ disseminated. The rate of spread of mistletoes is with- 

 out doubt very slow. Near Frazer, Colorado, on an old burn in the forest, 

 the rate of spread of Razoumofskya americana (Nutt.) Kuntze on the 

 lodge pole pines (Pinus contorta Loud.), is estimated to be from 6 to 

 12 feet per annum, where mechanical expulsion of the seeds aided by 

 winds are the controlling factors. Sporadic infections at much greater 

 distances are caused possibly bj^ birds or animals. 



Light is the most important factor in determining the spread of mis- 

 tletoes of species of both Razoumofskya and Phoradendron. Trees in 

 the open, and in more exposed conditions, whether on ridges or edges 

 of can3'ons or on level areas are most subject to attack by mistletoes on 

 account of the abundance of light. Mistletoes are stunted bv dense 



