1919] SARGENT, NOTES ON NORTH AMERICAN TREES. V. 65 



Betula fontinalis Saxg. — The type of this species is from Manitou, Colo- 

 rado, on the eastern foothills of the Rocky Mountains. The strobiles of 

 some of the Manitou plants are 4 cm. long and 10 or 12 mm. in diameter; 

 on other plants in the same locality the strobiles are only 2.5 cm. long and 

 5 mm. in diameter. Specimens from other parts of Colorado show a similiir 



variation in the size of the strobiles. The length and thickness of the stro- 

 biles and the shape of their scales have been used to distinguish B, Pipcri 

 Britt. from B. fontinalis. The longest strobiles of B, Piperi are 4 cm. long 

 and 5 cm, thick and are longer than the longest of B.fontinalisy but the size 

 of the strobile varies so much on different individuals that it has no value in 

 distinguishing species. The shape of the scales of the strobiles has also been 



fontinal 



distinguishing B. Piperi horn B.Jontinali 



than the middle one," and those of B, Piperi with " lateral lobes widely 



narrow 



These descriptions are true of the scales of some individuals^ but, as in other 



gre 



and 



Betula Piperi is a tree sometimes 16 or 17 m. high, with a tall single stem 

 occasionally 3 dm, in diameter. On the strength of its habit therefore B. 

 Piperi had perhaps best be distinguished as 



Betula fontinalis var. Piperi, n. var. — B. Piperi Britton in Bull. Tor- 

 rey Bot. Club, xxxi. 165 (1904). 



This appears to be a rare and local tree and to be confined to western 

 Washington where it occurs in the neighborhood of Pullman and Almota, 

 Wliitman County, and at Spokane, Lincoln County, where it probably 

 grows to its largest size. 



The Birch of this group from California has the short slender catkins of 

 some of the Colorado specimens of B. fontinalis and probably should be 

 referred to that species. 



I have seen Californian specimens from Sisson, Siskiyou County, J. G. 

 Jack, August 26, 1907; Metcalf's ranch, northeast base of Mt. Eddy, Siski- 

 you County, A, A. Heller, No. 12, 133, July 18, 1915 (in Herb. Arnold 

 Arboretum); Upper Sacramento River, Butte County, W. R. Dudley, August, 

 1899; Lone Pine Canyon and Cottonwood Canyon, Inyo County, E. L. 

 Morris, April 3, 1905; near Sisson and Salmon Mountains, Siskiyou Coimty, 

 W, R. Dudley, August 3, 1899, and August 26, 1901; Upper Sacramento 



River below Sheldon's Mill, W. /?. Dudley, August, 1897; Wyand Creek 

 Canyon near Deep Springs Valley, Inyo County, Roxana, S, Ferris, July 

 15, 1918; Round Mountain, J. F, Phares, August, 1915; Silver Canyon in 

 the Wliite Mountains east of Laws, Inyo County, A. A. Heller, No. 8260, 

 May 9, 190G (all in Dudley Herbarium, Leland Stanford Jr. University). 



