232 R. J. STEINHOFF 



STEINHOFF: Crossability of P. montioola was shortened to some 

 extent in my paper because it has been covered extensively in a forth- 

 coming paper 1 on genetics of western white pine. 



DUFFIELD: There were several not too impressive slides shown of 

 interspecies hybrids involving Pinus montioola. I'd like to point out, 

 however, that P. montioola is a pretty good parent, better than some of 

 the slides indicated. Many of the slides involved hybrids made at the 

 Institute of Forest Genetics in Placerville, California, and the P. 

 montioola parents used there came from high elevations in the Sierra 

 Nevada Mountains. I wouldn't say these trees were alpine dwarfs, but 

 relative to northern Idaho or other northwestern U.S. P. montioola, they 

 are slow-growing. We checked this at Placerville in 1949, finding that 

 P. montioola x P. strobus (or reciprocal) hybrids with the Sierra Nevada 

 P. montioola parent were much slower growing than those with the Idaho 

 parent. I think this would also apply to the other interspecies hybrids 

 involving P. montioola; most of them were made using the slow-growing 

 Sierra Nevada seed parent. 



BINGHAM: I would add to that remark by saying that in 1953 or 1954, 

 Dr. A. E. Squillace, then with my Experiment Station, planted trees of 

 several Sierra Nevada P. montioola x P. strobus hybrids (with some Sierra 

 Nevada P. montioola controls) at a location near Saltese in northwestern 

 Montana. Performance of the Sierra Nevada hybrids and P. montioola con- 

 trols was poor, compared to other nearby northern Idaho plantings of 

 hybrids and controls with northern Idaho P. montioola parents. I 

 shouldn't say too much here because different planting sites were 

 involved. 



KRIEBEL: I would suggest that because Dr. Heimburger has a tremen- 

 dous knowledge about many of these white pines, especially Pinus peuoe , 

 he be called upon to comment on these white pine species and hybrids. 



HEIMBURGER: We try to collect all the possible material in arboreta 

 in the form of grafts. We have been interested in Pinus peuoe Grisb. 

 because of all the exotic white pines in Canada it grows farthest to 

 the north — successfully so farther north than P. montioola or P. griffithii 

 McClell. Pinus peuoe also has been found to be resistant to the white 

 pine weevil Pissodes strobi , as well as moderately resistant to white 

 pine blister rust. Later this afternoon in my paper on blister rust 

 resistance tests in eastern North America (see Heimburger, these 

 proceedings), I will show some photographs and data on its resistance 

 to blister rust. This species is, of course, in itself rather useless, 

 because it grows too slow. But it has good form, good branching habit. 

 Also, its hybrids, particulary with P. montioola and P. griffithii , and 

 to a lesser extent with P. strobus, are very good. I will also cover 

 its precocious flowering this afternoon. 



1 Editor's note: The paper referred to 3 one of a series on genetics 

 of North American trees fostered by the Society of American Foresters 

 and published by the U.S. Forest Service, is: Bingham, R. T. 3 R. J. 

 Hoff s and R. J. Steinhoff. Genetics of western white pine. It will 

 probably be published in 1971 as one of a series of Forest Service, 

 Washington, B.C., Office Research Papers. 



