CURRENT LITERATURE 



Seed Production of Western White Pine. By R. Zon. Bulletin 

 210, U. S. Department of Agriculture. Contribution from the 

 Forest Service. Washington. D. C. 1915. Pp. 15. 



Mr. Zon points out in general the lack of knowledge regard- 

 ing seed production of American species and the difficulties 

 surrounding the problems of quantity, of frequency, of the deter- 

 mination of factors influencing these, and of the biological aspect 

 of seed production. 



The method employed in measuring the seed crop recognizes 

 that a unit area, not a single tree, and that not the amount of 

 cones but of viable seed is involved. Each sample area, from 

 one-quarter to one-half acre according to age, density and com- 

 position, should contain at least 100 trees of the principal species. 

 From practical consideration only the seed from sample trees 

 may be gathered, these sample trees to be chosen according to 

 different form and development of crown and taking into con- 

 sideration the part of the crown apt to bear seed. All trees are 

 divided into groups according to crown development (the usual 

 classification of dominancy — 7 to 10 classes) with their diameters 

 tallied. Since the diameter is practically a function of the crown, 

 one would think that finally diameter classes might suffice, but 

 instead the author requires a very close scrutiny of the habitus 

 of the crown from all sides. Curiously enough he makes the 

 statement that "in order to avoid errors of crown classification 

 the total number of trees on a sample plot must not exceed 100." 

 This seems to us a novel philosophy of the law of error ! or is 

 there a lapsus calami to be inferred ? 



Each tree is provided with a tag, giving number, diameter, crown 

 class, presence or absence of cones. Ten per cent, or more of 

 the trees in each class of cone-bearing ones are then selected and 

 carfully felled and cones collected for each tree separately and 

 properly labeled, and after ordinary drying the seeds are investi- 

 gated in all the directions that suggest themselves. 



We would point out that by this method of collecting cones 

 the chance of solving the problem of recurrence of seed produc- 

 tion on the same trees is lost. 



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