186 Fernald — Relationships of some American 



the Tyan-Shan Mountains as represented in the Gray Herba- 

 rium and by sheet ]^o. 25,339 in the U. S. National Herbarium, 

 such specimens as Y. Bailey's IS'o. 5 from South Dakota, 

 Coville and Leiberg's IS'o. 81 from IS'evada, and R. S. William's 

 1^0. 404 from Montana (sheets ISTos. 229,983, 275,933, and 

 290,087, U. S. Nat. Herb.) ; or Macoun's Devil's Lake plant, 

 Dawson's South Kootenai Pass Plant, and Macoun's Crow 

 Xest Pass Plant (Xos. 2,050, 23,623, and 24,368, Herb. GeoL 

 Surv. Can.) ; or Lake and Hull's No. 790 from Washington, 

 Rvdber^ and Bessey's No. 3,928 from Montana, Rydberg's No. 

 1,006 from the Black Hills, and A. Nelson's No. 1,647 from 

 Wyoming, we shall be further perplexed in separating the 

 American species from the Asian. Similar comparisons of 

 American specimens with the figures of B. fruticosa^ var. 

 Guneifolia (which by Kegel was identified with B. microphylla)^ 

 lead to the same result. In view of this evidence and the 

 essentially identical descriptions of Nuttall and Bunge, the 

 writer is still unable to see in Bettda fontinalis, Sargent {B. 

 occidentalism Nutt., not Hook. B. rhomhi/olia^ Nutt., not 

 Tausch) anything but B. mici^ophylla^ Bunge, of the moun- 

 tains of central Asia. 



§ Nanae. Shrubs : wings of the samaras narrower 

 than, or very rarely as broad as the achenes. 



The Dwarf Birches like the Canoe Birches present such 

 tendencies to intergradation that it is difiicult to draw clear 

 specific lines between them. Yet in America three fairly 

 marked species or centers of variation can be distinguished. 

 These are Betida pitmila^ L., with the young shoots normally 

 pubescent with long soft hairs, and quite glandless, but in an 

 extreme form with glands or resiniferous atoms mixed with 

 the long pnbescence ; B. glandidosa^ Michx., with the young 

 shoots glandular or resiniferous, at most puberulent with close 

 short hairs ; and B. nana^ L., a tiny shrub with the young 

 shoots puberulent or finely pubescent, but not glandular. Li 

 its typical form confined to arctic and alpine regions of Green- 

 land'^ Europe and Asia, B. nana is represented in America by 



Betula nana, var. Michauxii. 



A very dwarf birch with cinereous-puberulent glandless 

 branches and tiny suborbicular or flabelliform leaves has been 

 collected at various points in Newfoundland, Labrador, and the 

 Hudson Bay region, and has been referred to Betida nana, L., 

 or its var. fiahellifolia^ Hook. An examination of this material 

 shows that the strobiles are made u]3 of simple oblong scales, 

 instead of the deeply three-lobed scales characteristic of B. 

 nana and most other species of the genus. 



