272 R- T. BINGHAM 



crossability amongst 5-needled white pines will be needed. The objective 

 of this paper is to meet these two needs. 



The 5-needled white pine species discussed herein are identified 

 according to the usage of Critchfield and Little (1966) ; this taxonomic 

 treatment for white pines has been accepted by the IUFRO Committee on 

 (resistance to) White Pine Blister Rust, for use in all future communica- 

 tions . 



WHITE PINE TAXONOMY, BOTANICAL RANGE, AND CROSSABILITY 



Shown in Table 1 are the 21 5-needled white pines of Pinus Sub- 

 sections Cembrae, Strobi, and Balfourianae; the Latin names and authority 

 are as given by Critchfield and Little (1966). Also shown in the table 

 are: synonomy; common names; botanical ranges; and interspecies 

 crossability. 



The only additional information required here concerns two taxo- 

 nomical problems that are confounding clear communications between white 

 pine breeders. These problems are: (1) the controversy over which Latin 

 binomial (P. griffithii McClelland or P. w alii chi ana A. B. Jackson) is 

 correct or preferred for the Himalayan "blue pine"; and (2) the question 

 as to whether the "Japanese white pine" complex (P. parviflora Siebold 

 and Zuccarini) should be separated into a northern taxon (P. pentaphylla 

 Mayr) and a southern taxon (P. pentaphylla var .himekomatsu Makino or 

 P. himekomatsu Miyabe d, Kudo). The two taxa fall in distinct populations 

 separated by an easily located zone of contact and introgression, as 

 recognized by many Japanese botanists and dendrologists . Resolution of 

 these two problems was requested of the International Association for 

 Plant Taxonomy, August 18, 1969, by the Committee on White Pine Blister 

 Rust. 



RELATIVE BLISTER RUST RESISTANCE OF 5-NEEDLED WHITE PINES 



A composite, tentative ranking of blister rust resistance for 14 

 white pines of Subsections Cembrae, Strobi 3 and Balfourianae is presented 

 at the far right of Table 2. The ranking is based upon the observations 

 and experiments of five independent observers; data in Table 2 are 

 referenced to the observer's publications. However, to help the reader 

 to perceive the relative weight of the data, and understand how observa- 

 tions were converted into the numerical ratings of the table, the extent 

 of each observer's data and its conversion to numerical rankings is out- 

 lined below. 



Spaulding, 1925 and 1929: Spaulding's observations cover his own 

 earlier observations (Spaulding, 1922, and Pennington, et al. , 1921), 

 plus those of von Tubeuf (1897 and 1917), Moir (1924), Clinton (1919) 

 and Clinton and McCormick (1919) . They are based on rust canker occurrence 

 on a large number of white pines growing in natural stands or planted in 

 a large number of localities in Europe and North America as follows: 

 4 P. albioaulis trees in 3 localities; 7 P. aristata in 5 localities; 

 31 P. armandii in 5 localities; 14 P. ayacahuite in 7 localities; 11 P. 

 balfouriana in 8 localities; 1,000+ P. cembra and/or P. sibirioa in 33 

 localities; 340+ P. griffithii in 38 localities; 950+ P. flexilis in 19 

 localities; 8 P. koraiensis in 8 localities; 28+ P. lambertiana in 9 

 localities; 120+ P. montioola in 15 localities; 34+ P. parviflora in 10 



