BOOKS AND CURRENT LITERATURE 



Culture of Mistletoes. The first results of an extended series 

 of experiments on the culture of mistletoes have been published by- 

 Weir/ whose interest in these plants is that of the forester investigat- 

 ing one of the serious enemies of forest trees. The work was begun in 

 1911 and has been carried out in the northwestern states, chiefly at 

 Missoula, Montana. Some of the 3ultures were made in the open and 

 some of them in the greenhouse. The inoculations were effected by 

 soaking the seeds of the parasites and allowing them to dry on the 

 twigs and young branches of the hosts. No inoculations were at- 

 tempted on branches more than six years old. The success of the 

 method was demonstrated by the ease with which it was possible to 

 establish each of the parasites on the host tree which it most commonly 

 attacks, or for which it exhibits an "affinity," to use the wording of the 

 author. Species of Razoumofskya were also established on hosts which 

 they seldom inhabit in nature, as well as on related trees from regions 

 in which this genus of mistletoes does not occur. Important informa- 

 tion has thus been obtained that will aid in preventing the dissemina- 

 tion of western mistletoes by introducing nursery stock into eastern 

 forests or plantations in which new hosts might be attacked. For 

 example Razoumofskya lands mainly affects Larix occidentalis but can 

 be made to grow on Larix lyallii, L. europaea, L. leptolepis, Abies 

 grandis, Pinus ponderosa and P. contorta. Negative results were 

 secured from inoculations made on twelve other species of conifers and 

 on Alnus, Betula and Salix. Razoumofskya amev'cana is commonly 

 found on Pinus contorta and P. banksiana, but was made to grow on 

 six other pines, with negative results on fifteen species of Larix, Abies, 

 Picea, etc. It is pointed out that when the same strain of mistletoe is 

 grown on several hosts there are morphological differences between 

 the resulting plants, which have been used — in one or two cases — as a 

 basis for the description of distinct species. Other differences which 

 have been used in classification — notably those of color — appear to 

 be due to climatic conditions. — Forrest Shreve. 



' Weir, James R. Experimental investigations on the genus Razoumofskya. 

 Bot. Gaz. 67: 1-31. 1918. 



159 



